We have so far therefore three kinds of forms. (1) The pure self-subsistent form which never combines with matter. This embraces all the forms of the spiritual world. (2) Form which unites with body firmly and inseparably. These are the forms of the heavens and the stars. (3) Form which unites with body temporarily. Such are the forms of the bodies on the earth. The forms of the second and third classes cannot exist without bodies. The form of class number one cannot exist with body. To make the scheme complete, there ought to be a fourth kind of form which can exist with as well as without body. In other words, a form which unites with body for a time and then returns to its original state and continues to exist without body. Reason demands that the classification should be complete, hence there must be such a form, and the only one worthy of this condition is the soul of man. We thus have a proof of the immortality of the soul.[155] These are the ideas of the ancient sages, and we shall find that they are drawn from the Torah. Thus matter and form are indicated in the second verse of Genesis, "And the earth was _without form_ (Heb. Tohu) and _void_ (Heb. Bohu)." "Tohu" is matter; "Bohu" (בו הוא = בהו) signifies that through which matter gains existence, hence form. "Water" (Heb. Mayim) is also a general word for any of the various forms, whereas "light" (Heb. Or) stands for the pure subsistent form. By "firmament" (Heb. Rakiaʿ) is meant the second kind of form which unites with the pure matter in a permanent and unchangeable manner. "Let there be a _firmanent_ in the midst of the _waters_" (Gen. 1, 6) indicates that the "firmament" is embraced by the bright light of the first day, that is the universal form, from which all the other forms come. "And let it divide between _water_ and _water_" (_ib._) signifies that the "firmament" stands between the self-subsistent form and the third kind of form above mentioned, namely, that which unites with body and gives rise to substances changing their forms, like minerals and plants. The "luminaries" (Heb. Meorot) correspond to the second light mentioned above. We shall find also that the order of creation as given in Genesis coincides with the account given above in the name of the ancient sages.[156] It would seem as if the self-subsisting form and the two lights emanating from it are meant to represent the Intellect, Soul and Nature of the Neo-Platonic trinity respectively, and that Abraham bar Hiyya purposely changed the names and partly their functions in order to make the philosophical account agree with the story of creation in Genesis.