FIFTH ARTICLE: THE ANGELS ARE ABSOLUTELY IMMATERIAL QUESTION 50, A. 2

Avicebron held that matter was common to spirits and bodies because, as he said, there is something which they have in common. But the thing they have in common is nothing more than created essence as something capable of existence and limiting being. According to St. Thomas, it is impossible that a spiritual substance have any kind of matter. The operation of anything is after the manner of its substance, or operation follows being, or the mode of operation follows the mode of being. But intellection is an operation entirely immaterial, that is, intrinsically independent of matter, because it is specified of a universal object, by intelligible being, which abstracts from all matter. Thus the intellect is able to know the first principles of being, which are absolutely necessary and universal, above all contingent and particular being, and hence it can know the reasons for the being of things. Therefore a spiritual and intellectual substance is entirely immaterial.