וְהִנֵּה הָאִישׁ הַמִּתְקַדֵּשׁ בִּקְדֻשַּׁת בּוֹרְאוֹ אֲפִלּוּ מַעֲשָׂיו הַגַּשְׁמִיִּים חוֹזְרִים לִהְיוֹת עִנְיָנֵי קְדֻשָּׁה מַמָּשׁ, וְסִימָנָךְ אֲכִילַת קָדָשִׁים שֶׁהִיא עַצְמָהּ מִצְוַת עֲשֵׂה, וְאָמְרוּ זַ"ל (פסחים נט ב): כֹּהֲנִים אוֹכְלִים וּבְעָלִים מִתְכַּפְּרִים.
Behold, for the man sanctified with the holiness of his Creator, even his physical deeds become actual matters of holiness. A sign of this is in "the eating of temple offerings", which our sages of blessed memory said: "the priests eat and the owners obtain atonement" (Pesachim 59b).
וְתִרְאֶה עַתָּה הַהֶפְרֵשׁ שֶׁבֵּין הַטָּהוֹר לַקָּדוֹשׁ: הַטָּהוֹר, מַעֲשָׂיו הַחָמְרִיִּים אֵינָם לוֹ אֶלָּא הֶכְרֵחִים, וְהוּא עַצְמוֹ אֵינוֹ מִתְכַּוֵּן בָּהֶם אֶלָּא עַל צַד הַהֶכְרֵחַ, וְנִמְצָא שֶׁעַל יְדֵי זֶה יוֹצְאִים מִסּוּג הָרַע שֶׁבַּחָמְרִיּוּת וְנִשְׁאָרִים טְהוֹרִים, אַךְ לִכְלַל קְדֻשָּׁה לֹא בָּאוּ, כִּי אִלּוּ הָיָה אֶפְשָׁר בִּלְתָּם, כְּבָר הָיָה יוֹתֵר טוֹב.
You can now see the difference between the Pure man and the Holy man. The physical actions of the pure man are only to him as necessity. His only intent in doing them is on their necessary aspect. Through this, his actions escape the evil side of the physical and remain pure. But they do not enter the domain of Holiness, for if it were possible to do without them, it would already have been better for him.
וְעַל דֶּרֶךְ זֶה כָּל תַּשְׁמִישׁ שֶׁיִּשְׁתַּמְּשׁוּ מִדִּבְרֵי הָעוֹלָם אַחֲרֵי הֱיוֹתָם כְּבָר דְּבוּקִים לִקְדֻשָּׁתוֹ יִתְבָּרַךְ, הִנֵּה עִלּוּי וְיִתְרוֹן הוּא לַדָּבָר הַהוּא שֶׁזָּכוּ לִהְיוֹת תַּשְׁמִישׁ לַצַּדִּיק, וּכְבָר הִזְכִּירוּ זַ"ל בְּעִנְיַן אַבְנֵי הַמָּקוֹם שֶׁלָּקַח יַעֲקֹב וְשָׁם מְרַאֲשׁוֹתָיו (חולין צ"א ב): אָמַר רַבִּי יִצְחָק מְלַמֵּד שֶׁנִּתְקַבְּצוּ כֻּלָּן וְהָיְתָה כָּל אַחַת אוֹמֶרֶת עָלַי יַנִּיחַ צַדִּיק רֹאשׁוֹ.
In this way was all use they made of the things of this world. Since they were clinging to G-d's holiness, blessed be He, behold, it was an elevation and an enhancement for that thing which merited to be of use to a Tzadik (righteous person). Our sages already referred to the matter of the "stones at the place" which Yaakov took and put under his head: "Rabbi Yitzchak said: This tells us that all the stones gathered themselves together into one place and each one said: 'Upon me shall the righteous man rest his head'" (Chulin 91b).
כְּלָלוֹ שֶׁל דָּבָר עִנְיַן הַקְּדֻשָּׁה הוּא שֶׁיִּהְיֶה הָאָדָם דָּבֵק כָּל כָּךְ בֵּאלֹהָיו, עַד שֶׁבְּשׁוּם מַעֲשֶׂה אֲשֶׁר יַעֲשֶׂה לֹא יִפָּרֵד וְלֹא יָזוּז מִמֶּנּוּ יִתְבָּרַךְ, עַד שֶׁיּוֹתֵר יִתְעַלּוּ הַדְּבָרִים הַגַּשְׁמִיִּים אֲשֶׁר יְשַׁמְּשׁוּ לְאֶחָד מִתַּשְׁמִישָׁיו בְּמָה שֶׁהוּא מִשְׁתַּמֵּשׁ בָּהֶם, מִמָּה שֶׁיּוֹרֵד הוּא מִדְּבֵקוּתוֹ וּמַעֲלָתוֹ בְּהִשְׁתַּמְּשׁוֹ מִדְּבָרִים גַּשְׁמִיִּים.
The general principle of the matter: Holiness consists of one's clinging so much to his G-d that for any action he does, he will not separate nor budge from G-d, blessed be He, so that the physical things he uses will attain greater elevation than that which he diminishes in his clinging and level due to his using physical things.
וּכְבָר אָמַרְתִּי שֶׁאֵין הָאָדָם יָכוֹל לַעֲשׂוֹת בָּזֶה מִצִּדּוֹ, אֶלָּא לְהִתְעוֹרֵר בַּדָּבָר וּלְהִשְׁתַּדֵּל עָלָיו, וְזֶה אַחַר שֶׁכְּבָר יִמָּצְאוּ בּוֹ כָּל הַמִּדּוֹת הַטּוֹבוֹת שֶׁזָּכַרְנוּ עַד הֵנָּה מִתְּחִלַּת הַזְּהִירוּת וְעַד יִרְאַת הַחֵטְא, בָּזֹאת יָבֹא אֶל הַקֹּדֶשׁ וְיַצְלִיחַ, שֶׁהֲרֵי אִם הָרִאשׁוֹנוֹת חֲסֵרוֹת מִמֶּנּוּ, הֲרֵי הוּא כְּזָר וּבַעַל מוּם שֶׁנֶּאֱמַר בּוֹ וְזָר לֹא יִקְרַב (במדבר יח:ד).
I already mentioned that a man is unable to do this on his own. He can only rouse himself in the matter and strive towards it. And this is after he has already acquired all of the previous virtuous traits we mentioned, from the beginning of Watchfulness until the Fear of Sin. Only with this will he approach the Holy and succeed. For if he lacks the previous traits, he will be like an outsider or a blemished [Kohen] of which it is stated: "an outsider (non-Kohen) shall not come near" (Bamidbar 18:4).
אַךְ אַחֲרֵי הֲכִינוֹ אֶת עַצְמוֹ בְּכָל הֲכָנוֹת אֵלֶּה, אִם יַרְבֶּה לִדָּבֵק בְּתֹקֶף הָאַהֲבָה וְעֹצֶם הַיִּרְאָה בְּהַשְׂכָּלַת גְּדֻלָּתוֹ יִתְבָּרַךְ וְעֹצֶם רוֹמְמוּתוֹ, יַפְרִיד עַצְמוֹ מֵעִנְיְנֵי הַחֹמֶר מְעַט מְעַט, וּבְכָל פְּעֻלּוֹתָיו וּבְכָל תְּנוּעוֹתָיו, יְכַוֵּן לְבָבוֹ אֶל מַצְפּוּנֵי הַהִתְדַּבְּקוּת הָאֲמִתִּי, עַד שֶׁיַּעֲרֶה עָלָיו רוּחַ מִמָּרוֹם וְיַשְׁכִּין הַבּוֹרֵא יִתְבָּרַךְ אֶת שְׁמוֹ עָלָיו כְּמוֹ שֶׁעוֹשֶׂה לְכָל קְדֹשָׁיו.
But if after he has prepared himself with all these preparations, he persistently clings with powerful love and intense fear in pondering G-d's greatness and infinite exaltedness, he will separate himself from physical matters little by little and will direct his heart in all his actions and movements to the true inner clinging, until, a spirit from on high will pour upon him and the Creator will cause His Name to rest upon him, as He does with all of His holy ones.