בִּהְיוֹת אַדְמוּ"ר הַזָּקֵן בֶּן תֵּשַׁע שָׁנָה לָמַד חָכְמַת הַהַנְדָּסָה וְהַתְּכוּנָה. בֶּן עֶשֶׂר — סִדֵּר לוּחַ עַל חֲמֵשׁ עֶשְׂרֵה שָׁנָה. בִּהְיוֹתוֹ בֶּן שְׁנֵים עָשָׂר נִזְדַּמֵּן שֶׁלָּמַד בָּרַבִּים הִלְכוֹת קִדּוּשׁ הַחֹדֶשׁ לְהָרַמְבַּ"ם, וְלֹא מָצְאוּ הַגְּאוֹנִים, שֶׁהָיוּ בְּאוֹתוֹ מַעֲמָד, יְדֵיהֶם וְרַגְלֵיהֶם בְּבֵית הַמִּדְרָשׁ.

When the Alter Rebbe was nine years old, he studied geometry and astronomy. When he was ten, he composed a calendar1 for [the next] fifteen years.2 On one occasion, when he was twelve, he taught Hilchos Kiddush HaChodesh3 by Rambam in public, and the eminent scholars who were present were utterly unable to keep abreast of his presentation.4

To Fill In the Background

At other times, too, the Alter Rebbe’s prodigious Torah scholarship and spiritual sensitivity overflowed into seemingly-unrelated worldly disciplines.

The governor of the province of Vitebsk was the proud owner of a sundial that stood in the courtyard of his castle. What now bothered him was that for the last two years it had failed to give the correct time from two till five in the afternoon. None of the experts could solve the riddle.

Hearing that a brilliant young man had recently arrived in Vitebsk, he summoned the Alter Rebbe, who examined the sundial and said: “The Talmud states that at midday the sun is directly overhead; thus, nothing except the clouds can obscure it. In the afternoon, however, when the sun begins to move westward, it is possible for certain objects to block the sun’s rays.”

He added that in his estimation, there had to be a high hill about twelve or fifteen miles to the south, with tall trees growing on the hilltop.

The offending trees at the location specified were quickly chopped down, and once again the dial counted the sunny hours.

Needless to say, the Alter Rebbe’s fame soon spread far and wide.