In short, philosophers themselves, and medical men, even when it is their purpose to discourse about the mind, do in every instance inscribe on their title-page and table of contents, “De Anima” (“A treatise on the soul”). And that you may also have God’s voucher on the subject, it is the soul which He addresses; it is the soul which He exhorts and counsels, to turn the mind and intellect to Him. It is the soul which Christ came to save; it is the soul which He threatens to destroy in hell; it is the soul (or life) which He forbids being made too much of; it is His soul, too (or life), which the good Shepherd Himself lays down for His sheep. It is to the soul, therefore, that you ascribe the supremacy; in it also you possess that union of substance, of which you perceive the mind to be the instrument, not the ruling power.
Tertullian
A Treatise on the Soul
Chapter XIII