In "Ner Elohim" Abulafia lays down the foundations of his entire system of prophetic Kabbalah. It begins with an interpretation of the Blessing of the Priests, where Abulafia explains that the effect of the blessing depends on the knowledge of holy names, their composition, and their function. This leads him to describe the basic principles behind the workings of holy names and letter combinations, as outlined in the fundamental kabbalistic text of Sefer Yetzira, since "formation cannot exist without the combination of letters".