Part 2: They can appear in numerous different forms and likenesses: Many of the terms used in discussing the Sefirot have connotations of form and material substance. However, we certainly cannot say that the Sefirot themselves actually possess any kind of form or substance, for this would be heresy, and the Torah states explicitly: “For you did not see any form” (Deuteronomy 4:15).
As discussed earlier, the Sefirot are the powers of the Supreme Thought, and are “seen” (with spiritual vision) by the prophets or souls in a way comparable to the way a person “sees” the thoughts passing through his mind. Nevertheless, there is a great difference. For a person’s mind and thoughts are within him and are not Godly. Accordingly there is nothing to prevent us applying concepts of “form”, “likeness” and “appearance” of some subtle kind to the thoughts in a person’s mind, except that the form would be spiritual rather than physical. This is not so in the case of the Sefirot, which are the powers of the Thought (or “Mind”) of the Supreme Will, blessed be He. It is impossible to say that they possess any form at all, since we know that in all His aspects, the Emanator, blessed be His Name, completely transcends all the incidents and events that occur to those He created.