The commandment of the impurity of the eight swarming creatures: That the eight swarming creatures are impure and render impure, as it is stated (Leviticus 11:29), “And this shall be impure for you from the swarming creatures that swarm on the ground: the mole, the mouse and the lizard, etc.”
From the roots of the commandment, [we need to] preface [that] anyone who has intelligence will not have a doubt that there was never a man that grasped to know all wisdom to its end, that nothing of it be hidden from him. As behold even about our teacher Moshe, peace be upon him, they, may their memory be blessed, said (Rosh Hashanah 21b), “There are fifty gates of understanding, and they were all given over to Moshe, except for one.” And likewise, the wise King Shlomo said about himself (Ecclesiastes 7:23), “I said, ‘I will be wise,’ but it is distant from me.” And also any one with a brain in his skull will not have a doubt that God, may He be blessed, is the Father of wisdom and it is from Him — it comes out that it is all included in Him. And there is also not any doubt that the Father of all good would only command something to His creatures for their good and for their benefit, and to distance any injury from them. And therefore, when we grasp some of the commandments with our wisdom, to know the benefit that accrues to us from them, we shall rejoice about it. But when we do not grasp the benefit to us from them, with our wisdom, we must nonetheless think that with the extra wisdom that God, may He be blessed, has over every creature, He knows the benefit to us in that commandment. And therefore, He commanded us about it.
And they, may their memory be blessed, already informed us (Sanhedrin 21b) why we do not know the reason for all of the commandments; and they said that the thing is that it not become a stumbling block for us. And they brought a proof, as behold, the reason for three of them was revealed, and a great man of the world stumbled upon them. And let not a quibbler think to come against me with the metaphor that they, may their memory be blessed, said (Pesachim 28a), “The spoon carved by the carpenter will burn his mouth with mustard,” about that which I said now: That God, may He be blessed, hid the reasons from the commandments from us, and [yet] I have raised my hand to speak about them to my youth. As my teachers have already preceded me to speak several things about them in the Midrashim and in other places, by way of their simple understanding. And the depth of their wisdom, the strength of their understanding and their great holiness is stored in them — and even all the winds of the world cannot move them. And [regarding] anyone who is [able to] deepen counsel in their simple understanding, because he longs to “peer through the lattice,” to delight in the splendor of their vision and to gather from their leaves to gird himself with them - it is not fit to place blame upon him, but to bless him and to mention him for praise, “in the [place] that he is there”.
And now after this preface of ours — that the wisdom of God is greater than all wisdom and that He only commands a thing for our good and for our great benefit — we have no difficulty or question in all of the prohibition of foods and distancing of impurity, in everything that the benefit to us is not known and graspable by investigation; as we truthfully know, it is all for the good. And do not wonder, my son, about the matters of impurity, if it is very hidden from every creature — as it is possible that impurity injures the soul and makes it a little sick. And so [too,] have I heard the thing from the mouth of sages. And [it is] similar to that which they, may their memory be blessed, said (Yoma 39a), “‘And thus become impure (v’nitmeitem) through them’ (Leviticus 11:43) — it is written [spelled] ‘and you shall become foolish (nitamtem)’”; meaning to say that the springs of the intellect, which is the living soul, is spoiled a little with the matter of impurity.
And do not wonder about the intellect being spoiled with physical things, even though that is not its type. As due to the partnership of the soul with the body, such occurs to it regardless. And if so, we — the sons of man — in the poverty of our intelligence, do not know the soul and its nature. And [so] how are we to tire ourselves to know its healing or sickness by way of investigation? Is it not that there [can be] no strategy for physicians in healing until they know the essence of the sickness? And therefore regarding all of the distancings of impurity that are in the Torah, we should not dig for their roots until we come to complete knowledge of the matters of the soul — to know its nature, where it comes from and where it is going. And understand this and know it, as in it there is a bit of an answer to all the roots of the commandments of impurity and purity. [This is the case] to the point that there is like a veil over our faces regarding the novelty of the red heifer that renders the pure impure, but purifies the impure. And there too will we write at length about the matter, with God’s help, [so as] to receive reward for the effort to find desirable words.
The laws of the commandment: For example, that which they, may their memory be blessed, said (Mishnah Kelim 1:1) that eight swarming creatures are called a primary source (av) of impurity, meaning to say that they render a man and vessels impure by touch; and if the vessels are of clay, they render them impure once they enter its space (hollow). And this is the distinction that there is in the matter between that which is called a primary source and that which is called a derivative (velad) — as that which is called a primary source renders a man and vessels impure, but that which is called a derivative does not render a man and vessels impure. And the swarming creatures only render impure after they die, as it is stated (Leviticus 11:31), “in their being dead, he shall become impure.” And it is specifically these swarming creatures that render impure, but all other swarming creatures — the snake, the scorpion and all that are similar to them — do not render impure at all. And the law of the swarming creatures is that they do not render impure by carrying without touching [directly]; and that one that touches them does not render his clothes impure when they are upon him at the time that he touches them. And the measure of the impurity of the swarming creature is like [the size of] a lentil. As behold, we found that the Torah renders them pure undifferentiatedly, and there are some of these swarming creatures that are only like a lentil. And all of the swarming creatures combine to [the measure of] like a lentil — meaning to say, even a little of this one and a little of that one combine to [form the size of] a lentil, to render impure; such that you not say that the liability is only like a lentil from one [creature] by itself (Meilah 15b).
And the law of living flesh that is separated from a swarming creature, a complete limb, the kidney, the liver, and the tongue (Chullin 128b); the law of their blood, their tendons, their claws, their skins and their eggs (Meilah 17a); the law that anyone that is rendered impure by them is forbidden from eating the priestly tithe and consecrated food and entering the Temple until he immerses [in a ritual bath] — and the matter of immersion is like we will explain in its commandment (Sefer HaChinukh 175), with God’s help — and that even after his immersion, he is forbidden to eat even the priestly tithe until the sun sets, and afterwards he is pure and eats; and the rest of its details are elucidated in the Order of Tahorot, and mostly in Tractate Kelim and Tahorot. (See Mishneh Torah, Laws of Other Sources of Defilement 4.)
And [it] is practiced in every place and at all times by males and females, regarding that anyone who is rendered impure by swarming creatures is called impure and does not emerge from his impurity until he immerses in water, like his law. And nonetheless now that — on account of our iniquities — we do not have a Temple nor pure objects, we should not count it in the tally of commandments practiced. And anyone who is rendered impure — and even on purpose — at any time, does not have a sin with this; but rather he is not permitted to touch consecrated things until he becomes pure. And nonetheless anyone who understands, should distance impurity, as the soul is elevated with purity.
And Ramban, may his memory be blessed, wrote that we should not count all the laws of impurities in the tally of the commandments; and in his Book of Commandments (on Sefer HaMitzvot, Positive Commandments 96), he wrote a correct reason for his words, and the intellect inclines towards him. And from my desire for brevity in this composition, I did not want to write all of his arguments, but behold in Commandment 96 in his book, you will find the matter at length. And at the end of the matter he said that God prevented us from doing [certain] things in impurity, and [so] it remained to make known to us what thing is impure; and he said that they are the touching of the dead and the swarming creatures and the others — all that are mentioned in the Torah — and that we should not truthfully count them as commandments of their own. And this is [like] that which we said that the [Temple service] of someone with a blemish is prevented, and [so] it remained for us to know which thing is a blemish. And in fact we do not count each and every blemish as a commandment.
מִצְוַת טֻמְאַת שְׁמֹנָה שְׁרָצִים – לִהְיוֹת שְׁמֹנָה שְׁרָצִים טְמֵאִים וּמְטַמְּאִין, שֶׁנֶּאֱמַר (ויקרא יא כט) וְזֶה לָכֶם הַטָּמֵא בַּשֶּׁרֶץ הַשֹּׁרֵץ עַל הָאָרֶץ הַחֹלֶד וְהָעַכְבָּר וְהַצָּב וְגוֹ'.
The commandment of the impurity of the eight swarming creatures: That the eight swarming creatures are impure and render impure, as it is stated (Leviticus 11:29), “And this shall be impure for you from the swarming creatures that swarm on the ground: the mole, the mouse and the lizard, etc.”
מִשָּׁרְשֵׁי הַמִּצְוָה. הַקְדָּמָה, לֹא יִסְפֹּק כָּל מִי שֶׁיֵּשׁ בּוֹ דֵּעָה, שֶׁלֹּא הָיָה אָדָם מֵעוֹלָם שֶׁהִשִּׂיג לָדַעַת כָּל הַחָכְמָה עַד סוֹפָהּ, שֶׁלֹּא יִתְעַלֵּם לוֹ מִמֶּנָּה. שֶׁהֲרֵי אֲפִלּוּ עַל מֹשֶׁה רַבֵּינוּ ע"ה אָמְרוּ זִכְרוֹנָם לִבְרָכָה (ר"ה כא ב) חֲמִשִּׁים שַׁעֲרֵי בִּינָה הֵן, וְכֻלָּן נִמְסְרוּ לְמֹשֶׁה חוּץ מֵאֶחָד, וְכֵן שְׁלֹמֹה הַמֶּלֶךְ הֶחָכָם אָמַר עַל עַצְמוֹ (קהלת ז כג) אָמַרְתִּי אֶחְכָּמָה וְהִיא רְחוֹקָה מִמֶּנִּי. וְכֵן לֹא יִסְפֹּק כָּל מִי שֶׁיֵּשׁ בּוֹ מֹחַ בְּקָדְקֳדוֹ כִּי הַשֵּׁם יִתְבָּרַךְ הוּא אַב הַחָכְמָה, וּמֵאִתּוֹ נִמְצֵאת בּוֹ נִכְלֶלֶת כֻּלָּהּ. וְאֵין שׁוּם סָפֵק גַּם כֵּן כִּי אַב כָּל הַטּוֹבוֹת לֹא יְצַוֶּה דָּבָר [אֶת] (אֶל) בְּרִיּוֹתָיו רַק לְטוֹבָתָם וּלְתוֹעַלְתָּם וּלְהַרְחִיק כָּל נֶזֶק מֵעֲלֵיהֶם. וְעַל כֵּן בַּאֲשֶׁר נַשִּׂיג בְּחָכְמָתֵנוּ מִן הַמִּצְוֹת לָדַעַת הַתּוֹעֶלֶת הַמַּגִּיעַ לָנוּ בָּהֶן נִשְׂמַח בּוֹ. וְכַאֲשֶׁר אֵין אֲנַחְנוּ מַשִּׂיגִים מֵהֶם בְּחָכְמָתֵנוּ הַתּוֹעֶלֶת שֶׁלָּנוּ בָּהֶן, יֵשׁ לָנוּ לַחְשֹׁב עַל כָּל פָּנִים כִּי בְּיִתְרוֹן הַחָכְמָה אֲשֶׁר לַשֵּׁם יִתְבָּרַךְ עַל כָּל בְּרִיָּה יֵדַע הַתּוֹעֶלֶת אֲשֶׁר לָנוּ בְּאוֹתָהּ מִצְוָה וְעַל כֵּן צִוָּנוּ עָלֶיהָ.
From the roots of the commandment, [we need to] preface [that] anyone who has intelligence will not have a doubt that there was never a man that grasped to know all wisdom to its end, that nothing of it be hidden from him. As behold even about our teacher Moshe, peace be upon him, they, may their memory be blessed, said (Rosh Hashanah 21b), “There are fifty gates of understanding, and they were all given over to Moshe, except for one.” And likewise, the wise King Shlomo said about himself (Ecclesiastes 7:23), “I said, ‘I will be wise,’ but it is distant from me.” And also any one with a brain in his skull will not have a doubt that God, may He be blessed, is the Father of wisdom and it is from Him — it comes out that it is all included in Him. And there is also not any doubt that the Father of all good would only command something to His creatures for their good and for their benefit, and to distance any injury from them. And therefore, when we grasp some of the commandments with our wisdom, to know the benefit that accrues to us from them, we shall rejoice about it. But when we do not grasp the benefit to us from them, with our wisdom, we must nonetheless think that with the extra wisdom that God, may He be blessed, has over every creature, He knows the benefit to us in that commandment. And therefore, He commanded us about it.
וּכְבָר הוֹדִיעוּנוּ זִכְרוֹנָם לִבְרָכָה (סנהדרין כא ב) לָמָּה לֹא נֵדַע הַטַּעַם בְּכָל הַמִּצְוֹת, וְאָמְרוּ שֶׁהָיָה הַדָּבָר שֶׁלֹּא יִהְיֶה לָנוּ כִּשָּׁלוֹן בָּזֶה, וְהֵבִיאוּ רְאָיָה, שֶׁהֲרֵי שְׁלוֹשָׁה מֵהֶן נִתְגַּלָּה טַעְמָן וְנִכְשַׁל בָּהֶן גְּדוֹל הָעוֹלָם. וְאַל יַחְשֹׁב תּוֹפֵשׂ לָבוֹא עָלַי עַל הַמָּשָׁל שֶׁאָמְרוּ זִכְרוֹנָם לִבְרָכָה (פסחים כח א) כַּפָּא דְּחַק נַגָּרָא בֵּהּ נִשְׂרוֹף חַרְדָּלָא, בְּמַה שֶּׁאָמַרְתִּי עַכְשָׁו שֶׁהַשֵּׁם יִתְבָּרַךְ הֶעֱלִים מִמֶּנּוּ טַעֲמֵי הַמִּצְוֹת, וְאָנֹכִי הֲרִימוֹתִי יָדִי לְדַבֵּר בָּהֶן דָּבָר אֶל נְעָרַי, כִּי כְּבָר קְדָמוּנִי רַבּוֹתַי לְדַבֵּר בָּהֶן כַּמָּה דְּבָרִים בַּמִּדְרָשׁוֹת וּבִמְקוֹמוֹת אֲחֵרִים עַל צַד פְּשָׁטָן, וְעֹמֶק חָכְמָתָן וְחֹזֶק בִּינָתָן וְרֹב קְדֻשָּׁתָן הַגָּנוּז בְּתוֹכָן, וַאֲפִלּוּ כָּל הָרוּחוֹת שֶׁבָּעוֹלָם לֹא יָזִיזוּ אוֹתָן. וְכָל הַמַּעֲמִיק עֵצָה בִּפְשָׁטֵיהֶן וְיִשְׁתַּדֵּל לְחַדֵּשׁ דָּבָר בַּנִּגְלֶה שֶׁבָּהֶן כִּי יִכְסֹף לְהַצִּיץ מִן הַחֲרַכִּים לְהִתְעַנֵּג בְּזֹהַר מַרְאֵיהֶן וְלִלְקֹט מֵעֲלֵיהֶן לַחְגֹּר בָּהֶן, אֵין רָאוּי לָתֵת בָּזֶה עָלָיו אָשָׁם אַךְ לְבָרְכוֹ וּלְהַזְכִּירוֹ לִשְׁבָח בַּאֲשֶׁר הוּא שָׁם.
And they, may their memory be blessed, already informed us (Sanhedrin 21b) why we do not know the reason for all of the commandments; and they said that the thing is that it not become a stumbling block for us. And they brought a proof, as behold, the reason for three of them was revealed, and a great man of the world stumbled upon them. And let not a quibbler think to come against me with the metaphor that they, may their memory be blessed, said (Pesachim 28a), “The spoon carved by the carpenter will burn his mouth with mustard,” about that which I said now: That God, may He be blessed, hid the reasons from the commandments from us, and [yet] I have raised my hand to speak about them to my youth. As my teachers have already preceded me to speak several things about them in the Midrashim and in other places, by way of their simple understanding. And the depth of their wisdom, the strength of their understanding and their great holiness is stored in them — and even all the winds of the world cannot move them. And [regarding] anyone who is [able to] deepen counsel in their simple understanding, because he longs to “peer through the lattice,” to delight in the splendor of their vision and to gather from their leaves to gird himself with them - it is not fit to place blame upon him, but to bless him and to mention him for praise, “in the [place] that he is there”.
וְעַתָּה אַחֲרֵי הַקְדָּמָתֵנוּ זֹאת, שֶׁחָכְמַת הָאֵל גָּדְלָה עַל כָּל חָכְמָה וְכִי לֹא יְצַוֶּה דָּבָר רַק לְטוֹבָה לָנוּ וּלְתוֹעֶלֶת גְּדוֹלָה, אֵין לָנוּ קֻשְׁיָא וְלֹא שְׁאֵלָה בְּכֹל אִסּוּר הַמַּאֲכָלוֹת וְהַרְחָקַת הַטֻּמְאָה בְּכָל אֲשֶׁר לֹא יִהְיֶה הַתּוֹעֶלֶת לָנוּ יְדוּעָה וּמֻשָּׂג בַּחֲקִירָה, כִּי יָדַעְנוּ בֶּאֱמֶת שֶׁהַכֹּל לְטוֹב. וְאַל תִּתְמַהּ בְּנִי עַל עִנְיְנֵי הַטֻּמְאָה אִם הוּא נֶעֱלָם הַרְבֵּה עַל כָּל בְּרִיָּה, כִּי אֶפְשָׁר שֶׁהַטֻּמְאָה תַּזִּיק אֶל הַנֶּפֶשׁ וְתַחְלִיאָהּ קְצָת, וְכֵן שָׁמַעְתִּי הַדָּבָר מִפִּי חֲכָמִים, וּכְעֵין מָה שֶׁאָמְרוּ זִכְרוֹנָם לִבְרָכָה (יומא לט א) וְנִטְמֵאתֶם בָּם וְנִטַּמְתֶּם כְּתִיב כְּלוֹמַר שֶׁמַּעַיְנוֹת הַשֵּׂכֶל שֶׁהוּא הַנֶּפֶשׁ הַקַּיֶּמֶת מִתְקַלְקְלִים קְצָת בְּעִנְיַן הַטֻּמְאָה.
And now after this preface of ours — that the wisdom of God is greater than all wisdom and that He only commands a thing for our good and for our great benefit — we have no difficulty or question in all of the prohibition of foods and distancing of impurity, in everything that the benefit to us is not known and graspable by investigation; as we truthfully know, it is all for the good. And do not wonder, my son, about the matters of impurity, if it is very hidden from every creature — as it is possible that impurity injures the soul and makes it a little sick. And so [too,] have I heard the thing from the mouth of sages. And [it is] similar to that which they, may their memory be blessed, said (Yoma 39a), “‘And thus become impure (v’nitmeitem) through them’ (Leviticus 11:43) — it is written [spelled] ‘and you shall become foolish (nitamtem)’”; meaning to say that the springs of the intellect, which is the living soul, is spoiled a little with the matter of impurity.
וְאַל תִּתְמַהּ בְּהִתְקַלְקֵל הַשֵּׂכֶל בָּעִנְיָנִים הַגַּשְׁמִיִּים אַף עַל פִּי שֶׁאֵינוֹ מִינוֹ, כִּי מִפְּנֵי שִׁתּוּפָהּ שֶׁל נֶפֶשׁ עִם הַגּוּף יֶאֱרַע לָהּ כֵּן עַל כָּל פָּנִים. וְאִם כֵּן אֲנַחְנוּ בְּנֵי אִישׁ בַּעֲנִיּוּת דַּעְתֵּנוּ לֹא נֵדַע הַנֶּפֶשׁ וּמַהוּתָהּ וְאֵיךְ נִלְאֶה לָדַעַת רְפוּאָתָהּ אוֹ מַחֲלָתָהּ מִדֶּרֶךְ הַחֲקִירָה הֲלֹא לָרוֹפְאִים אֵין תַּחְבּוּלָה בִּרְפוּאָה עַד הַכִּירָם עִקַּר הַמַּחֲלָה, וְעַל כֵּן בְּכָל הַרְחָקוֹת הַטֻּמְאָה שֶׁיָּבוֹאוּ בַּתּוֹרָה, אֵין לָנוּ לְחַטֵּט אַחַר שָׁרְשֵׁיהֶן, עַד בּוֹאֵנוּ אֶל תַּכְלִית הַיְּדִיעָה בְּעִנְיְנֵי הַנֶּפֶשׁ לָדַעַת מַהוּתָהּ מוֹצָאָהּ וּמוֹבָאָהּ וְהָבֵן זֶה וְדָעֵהוּ, כִּי בּוֹ נִמְצָא קְצָת תְּשׁוּבָה עַל כָּל שָׁרְשֵׁי מִצְוֹת הַטֻּמְאָה וְהַטָּהֳרָה עַד אֲשֶׁר כִּמְעַט יִהְיֶה מַסְוֶה עַל פָּנֵינוּ בְּחִדּוּשׁ פָּרָה אֲדֻמָּה שֶׁמְּטַמְּאָה הַטָּהוֹר וּמְטַהֶרֶת הַטָּמֵא, וְגַם שָׁם (מצוה קצז) נַאֲרִיךְ בָּעִנְיָן בְּעֶזְרַת הַשֵּׁם לְקַבֵּל שָׂכָר בִּיגִיעָה לִמְצֹא דִּבְרֵי חֵפֶץ.
And do not wonder about the intellect being spoiled with physical things, even though that is not its type. As due to the partnership of the soul with the body, such occurs to it regardless. And if so, we — the sons of man — in the poverty of our intelligence, do not know the soul and its nature. And [so] how are we to tire ourselves to know its healing or sickness by way of investigation? Is it not that there [can be] no strategy for physicians in healing until they know the essence of the sickness? And therefore regarding all of the distancings of impurity that are in the Torah, we should not dig for their roots until we come to complete knowledge of the matters of the soul — to know its nature, where it comes from and where it is going. And understand this and know it, as in it there is a bit of an answer to all the roots of the commandments of impurity and purity. [This is the case] to the point that there is like a veil over our faces regarding the novelty of the red heifer that renders the pure impure, but purifies the impure. And there too will we write at length about the matter, with God’s help, [so as] to receive reward for the effort to find desirable words.
דִּינֵי הַמִּצְוָה. כְּגוֹן מַה שֶׁאָמְרוּ זִכְרוֹנָם לִבְרָכָה (כלים פ"א מ"א) שֶׁשְּׁמֹנָה שְׁרָצִים הֵם נִקְרָאִים אַב הַטֻּמְאָה כְּלוֹמַר שֶׁמְּטַמְּאִין אָדָם וְכֵלִים בְּמַגָּע, וְאִם הַכֵּלִים שֶׁל חֶרֶס מְטַמְּאִין אוֹתָן מִכֵּיוָן שֶׁיִּכָּנְסוּ בְּתוֹךְ אֲוִירוֹ. וְזֶהוּ הַחִלּוּק שֶׁיֵּשׁ בְּעִנְיָן הַטֻּמְאָה בֵּין מָה שֶׁנִּקְרָא אָב לְמָה שֶׁנִּקְרָא וָלָד, שֶׁהַנִּקְרָא אָב מְטַמֵּא אָדָם וְכֵלִים, וְהַנִּקְרָא וָלָד אֵינוֹ מְטַמֵּא אָדָם וְכֵלִים. וְהַשְּׁרָצִים אֵינָם מְטַמְּאִין עַד שֶׁיָּמוּתוּ, שֶׁנֶּאֱמַר (שם שם לא) הַנֹּגֵעַ בָּהֶם בְּמֹתָם יִטְמָא. וּשְׁמֹנָה שְׁרָצִים אֵלּוּ דַּוְקָא הֵם שֶׁמְּטַמְּאִין, אֲבָל כָּל שְׁאָר שְׁרָצִים נָחָשׁ וְעַקְרָב וְכַיֹּצֵא בָּהֶן, אֵינָם מְטַמְּאִין כְּלָל. וְדִין הַשְּׁרָצִים הוּא שֶׁאֵינָם מְטַמְּאִין בְּמַשָּׂא בְּלִי מַגָּע, וְהַנּוֹגְעָן שֶׁאֵינוֹ מְטַמֵּא בְּגָדִים שֶׁעָלָיו בִּשְׁעַת מַגָּעוֹ בָּהֶן, וְשִׁעוּר טֻמְאַת הַשֶּׁרֶץ בְּכַעֲדָשָׁה שֶׁהֲרֵי מָצִינוּ שֶׁהַתּוֹרָה טִמְּאָתַן סְתָם. וְיֵשׁ מֵהֶן שְׁרָצִים שֶׁאֵינָן אֶלָּא כַּעֲדָשָׁה. וְכָל הַשְּׁרָצִים מִצְטָרְפִין לְכַעֲדָשָׁה, כְּלוֹמַר אֲפִלּוּ מְעַט מִזֶּה וּמְעַט מִזֶּה מִצְטָרֵף לְכַעֲדָשָׁה לְטַמֵּא, שֶׁלֹּא תֹּאמַר אֵין הַחִיּוּב אֶלָּא בְּכַעֲדָשָׁה מֵאֶחָד לְבַד (מעילה טו ב).
The laws of the commandment: For example, that which they, may their memory be blessed, said (Mishnah Kelim 1:1) that eight swarming creatures are called a primary source (av) of impurity, meaning to say that they render a man and vessels impure by touch; and if the vessels are of clay, they render them impure once they enter its space (hollow). And this is the distinction that there is in the matter between that which is called a primary source and that which is called a derivative (velad) — as that which is called a primary source renders a man and vessels impure, but that which is called a derivative does not render a man and vessels impure. And the swarming creatures only render impure after they die, as it is stated (Leviticus 11:31), “in their being dead, he shall become impure.” And it is specifically these swarming creatures that render impure, but all other swarming creatures — the snake, the scorpion and all that are similar to them — do not render impure at all. And the law of the swarming creatures is that they do not render impure by carrying without touching [directly]; and that one that touches them does not render his clothes impure when they are upon him at the time that he touches them. And the measure of the impurity of the swarming creature is like [the size of] a lentil. As behold, we found that the Torah renders them pure undifferentiatedly, and there are some of these swarming creatures that are only like a lentil. And all of the swarming creatures combine to [the measure of] like a lentil — meaning to say, even a little of this one and a little of that one combine to [form the size of] a lentil, to render impure; such that you not say that the liability is only like a lentil from one [creature] by itself (Meilah 15b).
וְדִין (חולין קכח ב) בָּשָׂר חַי הַפּוֹרֵשׁ מִן הַשֶּׁרֶץ, וְאֵבָר אֶחָד שָׁלֵם, וְהַכּוֹלְיָא וְהַכָּבֵד וְהַלָּשׁוֹן, וְדִין (מעילה יז א) דָּמָן וְגִידָן וְצִפָּרְנָן וְעוֹרָן וּבֵיצָתָן. וְדִין כָּל שֶׁנִּטְמָא בָּהֶן שֶׁאָסוּר לֶאֱכֹל תְּרוּמָה וְקָדָשִׁים וְלִכָּנֵס לַמִּקְדָּשׁ עַד שֶׁיִּטְבֹּל, וְעִנְיַן טְבִילָה הוּא כְּמוֹ שֶׁנְּפָרֵשׁ בְּמִצְוָתוֹ (מצוה קעה) בְּעֶזְרַת הַשֵּׁם, וְאַף לְאַחַר טְבִילָתוֹ אָסוּר לֶאֱכֹל אֲפִילּוּ תְּרוּמָה עַד הֶעֱרֵב שֶׁמֶשׁ וְאַחַר כָּךְ טָהוֹר וְאוֹכֵל תְּרוּמָה, וְיֶתֶר פְּרָטֶיהָ מְבֹאָרִים בְּסֵדֶר טְהָרוֹת וּבָרֹב בְּמַסֶּכֶת כֵּלִים וּטְהָרוֹת [הלכות אבות הטומאה פ"ד].
And the law of living flesh that is separated from a swarming creature, a complete limb, the kidney, the liver, and the tongue (Chullin 128b); the law of their blood, their tendons, their claws, their skins and their eggs (Meilah 17a); the law that anyone that is rendered impure by them is forbidden from eating the priestly tithe and consecrated food and entering the Temple until he immerses [in a ritual bath] — and the matter of immersion is like we will explain in its commandment (Sefer HaChinukh 175), with God’s help — and that even after his immersion, he is forbidden to eat even the priestly tithe until the sun sets, and afterwards he is pure and eats; and the rest of its details are elucidated in the Order of Tahorot, and mostly in Tractate Kelim and Tahorot. (See Mishneh Torah, Laws of Other Sources of Defilement 4.)
וְנוֹהֶגֶת בְּכָל מָקוֹם וּבְכָל זְמַן בִּזְכָרִים וּנְקֵבוֹת. לְעִנְיָן שֶׁכָּל שֶׁנִּטְמָא בִּשְׁרָצִים נִקְרָא טָמֵא, וְלֹא יַעֲלֶה מִטֻּמְאָה עַד שֶׁיִּטְבֹּל בַּמַּיִם כְּדִינוֹ. וּמִכָּל מָקוֹם, עַכְשָׁו שֶׁאֵין לָנוּ בַּעֲוֹנֹתֵינוּ לֹא מִקְדָּשׁ וְלֹא טָהֳרוֹת. אֵין לָנוּ לִמְנוֹתָהּ בְּחֶשְׁבּוֹן מִצְוֹת הַנּוֹהֲגוֹת. וּמִי שֶׁמִּטַּמֵּא אֲפִילּוּ לְדַעַת בְּכָל זְמַן, אֵין עָלָיו חֵטְא בָּזֶה, אֶלָּא שֶׁאֵינוֹ רַשַּׁאי לִגַּע בַּקֳּדָשִׁים עַד שֶׁיִּטְהַר. וּמִכָּל מָקוֹם יֵשׁ לְכָל מֵבִין לְהַרְחִיק הַטֻּמְאָה, כִּי הַנֶּפֶשׁ מִתְעַלָּה בְּטָהֳרָה.
And [it] is practiced in every place and at all times by males and females, regarding that anyone who is rendered impure by swarming creatures is called impure and does not emerge from his impurity until he immerses in water, like his law. And nonetheless now that — on account of our iniquities — we do not have a Temple nor pure objects, we should not count it in the tally of commandments practiced. And anyone who is rendered impure — and even on purpose — at any time, does not have a sin with this; but rather he is not permitted to touch consecrated things until he becomes pure. And nonetheless anyone who understands, should distance impurity, as the soul is elevated with purity.
וְכָתַב הָרַמְבַּ"ן זִכְרוֹנוֹ לִבְרָכָה, שֶׁאֵין לָנוּ לַחְשֹׁב בְּמִנְיַן הַמִּצְוֹת כָּל דִּינֵי הַטֻּמְאוֹת. וּבְסֵפֶר הַמִּצְוֹת שֶׁלּוֹ (בסהמ"צ עשה צו) כָּתַב טַעַם נָכוֹן לִדְבָרָיו, וְהַדַּעַת נוֹטָה אַחֲרָיו, וּמֵחֶפְצִי בַּקִּצּוּר בְּחִבּוּר זֶה, לֹא רָצִיתִי לִכְתֹּב כָּל טַעֲנוֹתָיו. הִנֵּה בְּמִצְוַת צ"ו בְּסִפְרוֹ תִּמְצָא הָעִנְיָן בַּאֲרֻכָּה. וּבְסוֹף הָעִנְיָן אָמַר, שֶׁהַשֵּׁם מְנָעָנוּ מֵעֲשׂוֹת הַדְּבָרִים בְּטֻמְאָה וְנִשְׁאַר עָלֵינוּ לְהוֹדִיעֵנוּ אֵיזֶה דָּבָר הוּא הַטֻּמְאָה, וְאָמַר שֶׁהִיא נְגִיעַת הַמֵּת וְהַשְּׁרָצִים וְזוּלָתָם כָּל הַנִּזְכָּרִים בַּתּוֹרָה. וְשֶׁאֵין לָנוּ לִמְנוֹתָן בֶּאֱמֶת מִצְוֹת בִּפְנֵי עַצְמָן. וְזֶהוּ שֶׁאָמַרְנוּ שֶׁהַקְרָבַת בַּעַל מוּם נִמְנַעַת, וְנִשְׁאַר עָלֵינוּ לָדַעַת אֵיזֶה דָּבָר הֵן הַמּוּמִין, וּבֶאֱמֶת לֹא נִמְנֶה כָּל מוּם וּמוּם מֵהֶם מִצְוָה.
And Ramban, may his memory be blessed, wrote that we should not count all the laws of impurities in the tally of the commandments; and in his Book of Commandments (on Sefer HaMitzvot, Positive Commandments 96), he wrote a correct reason for his words, and the intellect inclines towards him. And from my desire for brevity in this composition, I did not want to write all of his arguments, but behold in Commandment 96 in his book, you will find the matter at length. And at the end of the matter he said that God prevented us from doing [certain] things in impurity, and [so] it remained to make known to us what thing is impure; and he said that they are the touching of the dead and the swarming creatures and the others — all that are mentioned in the Torah — and that we should not truthfully count them as commandments of their own. And this is [like] that which we said that the [Temple service] of someone with a blemish is prevented, and [so] it remained for us to know which thing is a blemish. And in fact we do not count each and every blemish as a commandment.