The type of intelligent nature is most perfectly actualized in the angels, whose essence and operation are purely spiritual, so far as created, finite nature and operation can be purely spiritual. Whatever is intelligible or conceivable of finite, intellectual activity as connatural, or intrinsically included in the essence of created spirit, is to be attributed to them. The notion of any composition of nature in the angels, or hypostatic union of their pure, spiritual substance with another material substance distinct from it, is wholly gratuitous. It destroys the distinctive type of the angelic nature and the specific difference between it and human nature. It has no foundation in reason except the baseless supposition that a distinct {11} corporeal organization is necessary to the exercise of created intelligence. Nor has it any solid support from tradition or extrinsic authority. Some of the fathers are cited as maintaining it. Their language is, however, for the most part explained by the best theologians as indicating not the union of the angelic spirit to a distinct subtle corporeity, but the existence of something analogous to matter in the angelic spirit itself. The angels are called corporeal existences, because their essence is extrinsic to the divine essence, and extrinsecation attains its extreme limit in matter; also because their potentiality is not completely reduced to act, and their operation is limited by time and space. This appears to be also the notion advocated by Leibnitz, and the exposition of the nature of material substance given above, in accordance with his philosophy, removes all difficulty from the subject. The conception of the angelic essence as completely free from all composition with a distinct material substance, is also at least more evidently in harmony with the decree _Firmiter_ of the Fourth Council of Lateran, than any other. "Firmiter credimus et simpliciter confitemur, quod unus est solus verus Deus aeternus. . . . . qui sua omnipotenti virtute simul ab initio temporis, utramque de nihilo condidit creaturam, spiritualem et corporalem, angelicam videlicet et mundanam; ac deinde humanam quasi communem ex spiritu et corpore constitutam." "We firmly believe and confess with simplicity, that there is one only true eternal God . . . . who by his own almighty power simultaneously from the beginning of time made out of nothing both parts of the creation, the spiritual and the corporeal, that is, the angelical and the mundane: and afterwards the human creature, as it were of a nature in common with both, constituted from spirit and body."