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.
Duns Scotus: (13th c. British philosopher.) The soul is a created something, the basis of all finite existence, including corporeal matter itself.
Albert Magnus: (13th c.) Held that the active intellect is a part of the soul, and is immortal by virtue of its community with God.
Gassendi: (French philosopher, 17th c.) There is no evidence of the spirituality of the soul.
Malebranche: (Priest and philosopher, 17th c.) We see all in God, who is in fact our soul.
Locke: (17th c.) Matter may think, and God may communicate thought to matter.
Paracelsus: (15th c.) Taught there were four souls—vegetal, sensitive, rational, and spiritual. Campanella demonstrates this last by the fact that carcasses bleed at the sight of the murderer.
Mansel: (“Philosophy of Consciousness,” p. 327.) We are not authorized to say that we know the soul to be simple, and that, therefore, it is indestructible; but only that we do not know the soul to be compound, and, therefore, that we cannot infer its mortality from the analogy of bodily dissolution.
“Buck’s Theo. Dic.” defines soul: That vital, immaterial, active substance, or principle in man, whereby he perceives, remembers, reasons, and wills. It is rather to be described as to its operations than to be defined as to its essence. Various, indeed, have been the opinions of philosophers concerning its substance.