and their relation in physical substances (); the substance which underlies the corporeality of the world (); proofs of the existence of intermediaries between God and the physical world (, lit. "intelligibiles"); proofs that these "intelligibiles" are likewise constituted of matter and form; universal matter and universal form. Fons Vitæ posits that the basis of existence and the source of life in every created thing is a combination of "matter" () and "form". The doctrine of matter and form informed the work's subtitle: "De Materia et Forma." Its chief doctrines are: everything that exists may be reduced to three categories: God; matter and form (i.e. Creation); will (an intermediary). All created beings are constituted of form and matter. This holds true for both the physical world () and the spiritual world (), which latter are the connecting link between the first substance (i.e. the Godhead, ) and the physical world (, lit. "substance divided into nine categories"). Matter and form are always and everywhere in the relation of "sustinens" and "sustentatum", "propriatum" and "proprietas": substratum and property or attribute. Influence within Judaism Though Gabirol as a philosopher was ignored by the Jewish community, Gabirol as a poet was not, and through his poetry, he introduced his philosophical ideas. His best-known poem, Keter Malkut ("Royal Crown"), is a philosophical treatise in poetical form, the "double" of the Fons Vitæ. For example, the eighty-third line of the poem points to one of the teachings of the Fons Vitæ; namely, that all the attributes predicated of God exist apart in thought alone and not in reality. Moses ibn Ezra is the first to mention Gabirol as a philosopher, praising his intellectual achievements, and quoting several passages from the Fons Vitæ in his own work, Aruggat ha-Bosem. Abraham ibn Ezra, who cites Gabirol's philosophico-allegorical Bible interpretation, borrows from the Fons Vitæ both in his prose and in his poetry without giving due credit. The 12th-century philosopher Joseph ibn Tzaddik borrows extensively from the "Fons Vitæ" in his work Microcosmos. Another 12th-century philosopher, Abraham ibn Daud of Toledo, was the first to take exception to Gabirol's teachings. In Sefer ha-Kabbalah he praises Gabirol as a poet. But to counteract the influence of ibn Gabirol the philosopher, he wrote an Arabic book, translated into Hebrew under the title Emunah Ramah, in which he reproaches Gabirol for having philosophized without any regard to the requirements of the