All Tzaddikim put their essence into their Torah, similar to the way G‑d put His essence into the Torah. This is alluded to in the first word of the Ten Commandments - ‘anochi’ (‘I’). Our Sages tell us that this word is an acronym for ‘anoh nafshi k’sovis y’hovis’ - ‘I wrote and put My Soul [into it]’ (Shabbat, 105A). We see this point stressed by the Rebbe Rashab. Before leaving this world, he said, ‘I am going to heaven, but the writings I am leaving for you.’ By this he meant to say that through his writings, he himself was remaining with them, since he put his essence into his Torah.