The Kuzari (c. 1140)

Judah Halevi's dialogue, written in Arabic as Kitāb al-Khazarī and translated into Hebrew by Ibn Tibbon in 1167: the king of the Khazars interviews a philosopher, a Christian, a Muslim and finally a Jew, and the book is the last conversation.

It matters to this room for one small aside. Asked about the swaying of Jews at study and prayer, Halevi gives a deflating and entirely practical answer — books were scarce, several students shared one manuscript, and each leaned in to read and rocked back to give the next man his turn. The habit survived the scarcity that produced it, which is what habits do. Set that beside the Zohar's flame, written a century and a half later, and you have two complete explanations of one motion: an accident of book-supply, and the visible behaviour of the soul. This app declines to pick. Part II; the section numbering varies between editions and translations.