וְסִפֵּר, שֶׁכָּל לִמּוּדוֹ בָּא לוֹ בִּיגִיעָה גְּדוֹלָה. The Rebbe told us that all his studies required great effort.
כִּי בִּתְחִלָּה הָיָה לוֹמֵד מִשְׁנָיוֹת וְלֹא הָיָה מֵבִין לִמּוּדוֹ וְהָיָה בּוֹכֶה הַרְבֵּה לִפְנֵי ה' יִתְבָּרַךְ שֶׁיָּאִיר עֵינָיו. וְהָיָה בּוֹכֶה וּבוֹכֶה כָּל כָּךְ עַד שֶׁזָּכָה שֶׁיּוּכַל לִלְמוֹד מִשְׁנָיוֹת, וְכֵן אַחַר־כָּךְ לָמַד שְׁאָר סְפָרִים וְלֹא הָיָה מֵבִין גַּם כֵּן וְהָיָה בּוֹכֶה וּבוֹכֶה גַּם־כֵּן הַרְבֵּה מְאֹד עַד שֶׁזָּכָה לַהֲבִינָם. וְכֵן בְּלִמּוּד זֹהַר וְכִתְבֵי הָאֲרִ"י, ז"ל, הָיָה בּוֹכֶה גַּם כֵּן הַרְבֵּה עַד שֶׁזָּכָה לְהָבִין. When he began to learn Mishnah16 The earlier part of the Talmud, redacted by Rabbi Yehudah HaNasi in 204 C.E. Mishnah is usually the first thing a child studied after completing the Torah. as a young child, he did not understand it. He wept and wept until he was able to understand the Mishnah. Later, when he studied more advanced works, he again found himself unable to comprehend them. Again he cried bitterly until he was worthy of understanding. This was true even of such esoteric studies as the Zohar and the writings of the Ari, where understanding only came after long and bitter weeping.
וְאָמַר: שֶׁבִּתְחִלָּה בְּכָל סֵפֶר וָסֵפֶר שֶׁלָּמַד לֹא הָיָה מֵבִין וְהָיָה קָשֶׁה לוֹ הַרְבֵּה וְלֹא הָיָה יָכוֹל לַעֲמֹד עַל פְּשׁוּטָן שֶׁל דְּבָרִים. וְהָיָה לוֹ יִסּוּרִים גְּדוֹלִים מִזֶּה וְהָיָה לִמּוּדוֹ בִּיגִיעָה גְּדוֹלָה, וְאַף־עַל־פִּי־כֵן לָמַד הַרְבֵּה מְאֹד. כִּי הָיָה מְחַזֵּק עַצְמוֹ מְאֹד וְהַכֹּל זָכָה עַל־יְדֵי תְּפִלָּתוֹ וּבְכִיָּתוֹ כַּנַּ"ל. He said that when he began to study any work, he did not understand it. It was very difficult for him and he could not grasp its straightforward meaning. This greatly distressed him. His studies required prodigious effort, but nevertheless, he studied a lot by constantly encouraging himself. He achieved it all through his prayer and weeping.