In the early 1890s, Abraham Isaac Kook—later the first Ashkenazi chief rabbi of Mandatory Palestine—served as the rabbi of the Russian shtetl of Žeimelis, where he kept a Hebrew-language spiritual diary. Although about half of this material made it into his published works, the rest did not, until the manuscript was edited and published in Israel earlier this year. The diary, as Yehudah Mirsky explains, reflects a crucial period in Kook’s intellectual development: all the elements of his unique mystical theology are present, but without his application of these ideas to the spiritual rebirth of the Jewish people through the return to Zion, which eventually became the hallmark of his thought:

The notebook Kook called M’tsiot Katan freely mixes halakhic, philosophical, [homiletic], and kabbalistic discussion and affords an indispensable window into Kook’s development in those crucial years of his first rabbinate. We can, for now, present an overview of this work, and in particular of the first appearances here of philosophical and theological themes which set the terms of many of Kook’s future [writings]. This in turn helps us better understand the roots of his thought and its trajectory over time.

Two questions predominate in this collection. The first is the relationship between the body, mind, and soul, and its corollary of the status of nature in God’s creation. The second is the relationship between Jewish and Gentile morality. . . .

Most interestingly, Kook relates [his] concern with the relationship between the body and the mind to a more social and political question—the meaning and significance of disagreement, and of heresy, an interest of his echoing the vivid ideological disagreements of the time and a question that would preoccupy him for the rest of his life.

Of course, the natural body’s potential to corrupt the mind was for centuries a staple of Jewish ethics and moral philosophy. What is striking here, though, is [Kook’s view of this] failing as the corruption of a fundamentally good, God-given nature, a nature that includes moral sentiments. This [view] in turn makes possible, for him, a recasting of principled debate and disagreement as the working-out of the various elements of that God-given sense of the good. Thus, he says, peace is the fundamental character of the world, and the multiplicity of contending views of the good all point toward the final end point—peace—which will emerge precisely from the cauldron of disagreement.