Athenagoras: (2d c.) The soul is spiritual, but with a spirituality subject to material tendencies.
Origen: (3d c.) The soul is neither spirit nor matter.
Augustine: (4th c.) The soul has neither length, breadth, nor thickness. It acts on the body through the corporeal substances of light and air, which substances are mingled through the denser parts of the body. The commands of the soul are first communicated to this subtile matter, and by it immediately conveyed to the heavier elements.
Tertullian: (Latin father, about 160.) The soul has the human form, the same as its body, only it is delicate, clear, and ethereal. Unless it were corporeal, how could it be effected by the body, be able to suffer, or be nourished within the body?
St. Ambrose: (4th c.) We know nothing but what is material, excepting only the ever venerable Trinity.
St. Hilary: (5th c.) There is nothing created which is not corporeal, neither in heaven nor in earth, neither visible nor invisible; all is formed of elements; and souls, whether they inhabit a body, or are without a body, have always a corporeal substance.
Gregory Nazianzen: (4th c.) Soul, or spirit, is composed of two properties--motion and diffusion.
Bishop Nemesius: (5th c.) The soul is an immaterial substance. It is involved, as Plato taught, in eternal, self-produced motion, from which the motion of the body is derived. The pre-existence of the soul proves its supra-sensible character, and its immortality.
Faustus: (Bishop of Regium, in Gaul, A. D. 470.) All created things are matter; the soul being composed of air, God alone is incorporeal.
Mamertus: (In reply to the bishop.) Man was made in the image of God. Now, as there can be no likeness to God in matter, therefore it must be found in the soul, therefore the soul is immaterial. The soul is present in every part of the body as well as in the whole, just as God is present in the whole universe, otherwise a part of it would be lost when any portion of the body is cut off. The soul is not contained in the body, but in reality contains it. Hence, it must be immaterial, for no material substance can at once contain the body and be within it as its animating principle.
Thomas Aquinas: (13th c.) The soul is the Actuality of body, as heat, which is the source whence bodies are made hot, is not body, but a sort of actuality of body. The soul of man is an independent substance.