Nefesh HaChayim, Reb Itzele's Long Annotation

And when the Holy One (blessed be He) desired to impute merit to Israel, for that reason he heaped upon them [a vast] Torah and [many] commandments. For by their effect they will be able to subdue the evil inclination and to arouse the supernal roots that are drawn from the name YHV”H (blessed be He): to refine his entire body, so that all the vessels of his brain484Heb.: mo-kho are filled with thoughts of Torah; and with his entire hearts/minds485Heb.: l’va-vo he’ll contemplate words of Torah day and night; and with his entire body486Heb.: goo-foe he’ll be involved with the commandments that are fulfilled by physical action. For Torah is the root of all supernal roots that pre-dated the creation of the world.