Now listen to the correct and clear explanation of the verse in its simplicity. The Holy One, blessed be He, created all things from absolute non-existence. Now we have no expression in the sacred language for bringing forth something from nothing other than the word bara (created). Everything that exists under the sun or above was not made from non-existence at the outset. Instead He brought forth from total and absolute nothing a very thin substance devoid of corporeality but having the power of potency, fit to assume form and to proceed from potency, fit to assume form and to proceed from potentiality into reality. This was the primary matter created by G-d; it is called by the Greeks hyly (matter). After the hyly, He did not create anything, but he formed and made things with it, and from this hyly He brought everything into existence and clothed the forms and put them into a finished condition.
Know that the heavens and all that is in them consists of one substance, and the earth and everythign this is in it consists of one substance. The Holy One, blessed be He, created these two substances from nothing; they alone were created, and everything else was constructed from them.
This substance, which the Greeks called hyly, is called in the sacred language tohu, the word being derived from the expression of the Sages: “betohei (when the wicked bethinks himself) of his doings in the past.†If a person wants to decide a name for it [this primordial matter], he may bethink himself, change his mind and call it by another name since it has taken on no form to which the name should be attached. The form which this substance finally takes on is called in the sacred language bohu, which is a composite word made up of the two words bo hu (in it there is [substance]). This may be compared to the verse, Thou art not able 'asohu' (to perform it, Exodus 18:18) in which case the word asohu is missing a vav and an aleph [and I is a composite of the two words] aso hu. It is this which Scripture says, And he shall stretch over it the line of 'tohu' (confusion) and the stones of 'bohu.' (Isaiah 34:11) [The tohu in Hebrew or the hyly in Greek] is the line by which the craftsman delineates the plan of his structure and that which he hopes to make. This is derived from the expression, Kavei (Hope) unto G-d (Psalms 27:14). The stones are forms in the building. Similarly it is written, They are acconted by Him as nought and 'tohu,' (Isaiah 40:17) as tohu comes after nothingness and there is nothing yet in it.
So the Rabbis have also said in Sefer Yetzirah: “He created substance from tohu, and made that which was nothing something.â€
They have furthermore said in the Midrash of Rabbi Nechunya ben Hakanah: “Rabbi Berachyah said: “What is the meaning of the verse, And the earth was 'tohu' (without form) 'vavohu' (and void)? What is the meaning of the word “was?†It had already been tohu. And what is tohu? It is a thing which astonishes people. It was then turned into bohu. And what is bohu? It is a thing which has substance, as it is written, [bohu is a composite of the two words] “bo hu†(in it there is subtance)