The Treatise on the Left Emanation () is a Kabbalistic text by Rabbi Isaac ben Jacob ha-Cohen, who with his brother Jacob traveled in Spain and Provence in the period of 1260âÂÂ1280.
Scholars credit this text with being the first to present a "comprehensive concept of evil", bearing a striking resemblance to that found in Gnosticism. It is also the first to treat Samael and Lilith as a couple, likely inspiring later such depictions in the Zohar.
Isaac may be the pseudepigraphic author of other texts including the Pseudo-R. Eleazar Responsum, and the Pseudo-R. Yehushiel Responsa.