The Alter Rebbe distinguishes between a complete tzaddik (tzaddik gamur) who loves God with all his heart and has no love for worldly pleasures at all, and an incomplete tzaddik who still retains some minor residual pull toward physicality. Even the incomplete tzaddik is rare and exceptional.
וְהִנֵּה, מַדְרֵגָה זוֹ מִתְחַלֶּקֶת לְרִבְבוֹת מַדְרֵגוֹת בְּעִנְיַן בְּחִינַת מִיעוּט הָרָע הַנִּשְׁאָר מֵאַחַת מֵאַרְבַּע יְסוֹדוֹת הָרָעִים, וּבְעִנְיַן בִּיטּוּלוֹ בְּמִיעוּטוֹ בְּשִׁשִּׁים עַל דֶּרֶךְ מָשָׁל, אוֹ בְּאֶלֶף וּרְבָבָה וְכַיּוֹצֵא עַל דֶּרֶךְ מָשָׁל. וְהֵן הֵם בְּחִינוֹת צַדִּיקִים הָרַבִּים שֶׁבְּכָל הַדּוֹרוֹת, כִּדְאִיתָא בַּגְּמָרָא, דִּתַמְנֵיסַר אַלְפֵי צַדִּיקֵי קָיְימֵי קַמֵּיהּ הַקָּדוֹשׁ־בָּרוּךְ־הוּא. אַךְ עַל מַעֲלַת צַדִּיק גָּמוּר, הוּא שֶׁאָמַר רַבִּי שִׁמְעוֹן בֶּן יוֹחָאִי: ״רָאִיתִי בְּנֵי עֲלִיָּה וְהֵם מוּעָטִים כוּ׳״, שֶׁלָּכֵן נִקְרָאִים ״בְּנֵי עֲלִיָּה״, שֶׁמְּהַפְּכִין הָרָע וּמַעֲלִים אוֹתוֹ לִקְדוּשָּׁה, כִּדְאִיתָא בַּזֹּהַר בַּהַקְדָּמָה, שֶׁכְּשֶׁרָצָה רַבִּי חִיָּיא לַעֲלוֹת לְהֵיכַל רַבִּי שִׁמְעוֹן בֶּן יוֹחָאִי, שָׁמַע קָלָא נָפִיק וְאָמַר: ״מַאן מִנְּכוֹן דִּי חֲשׁוֹכָא מְהַפְּכָן לִנְהוֹרָא וְטָעֲמִין מְרִירוּ לְמִיתְקָא עַד לָא יֵיתוּן הָכָא וְכוּ׳״:
Now, this grade is subdivided into myriads of degrees in respect of the quality of the minute evil remaining [in him] from any of the four evil elements, as well as in relation to its proportionate abnegation by reason of its minuteness, such as, by way of example, one in sixty, or in a thousand, or in ten thousand, and the like. Such are the gradations of the numerous righteous men who are to be found in every generation, as mentioned in the Gemara, viz., “Eighteen thousand righteous men stand before the Holy One, blessed is He.” However, it is with regard to the superior quality of the “completely righteous” that Rabbi Shimon bar Yochai said, “I have seen superior men (benei aliyah), and their numbers are few….” The reason for their title of “superior men” is that they convert evil and make it ascend to holiness, as is written in the Zohar in the Introduction, that when Rabbi Chiya wished to ascend to the hechal (heavenly shrine) of Rabbi Shimon bar Yochai, he heard a voice come out and say, “Which of you, before coming here, has converted darkness into light and bitter taste into sweetness? [Otherwise] do not approach here,” and so forth.