Nefesh HaChayim, An Introduction by the Author's Son

And it’s not surprising that he earned merit for himself and enabled the public to be worthy of merit, for from his youth he bore the yoke of Torah with tremendous assiduousness. And at the age of fourteen he learned fixedly with his older brother, the genius, our teacher Simkha (OBM). And he acquired knowledge day and night. And our elders told us the story of how when the light of candles was not available, the light of the moon was enough for them to learn at night. And at that time they received the path of Torah from the rabbi of rabbis, genius of geniuses, the lion of the supernal residence, Rabbi Aryei Leib (in Eden is his resting place), the author of the Shaagaht Aryei[*].