Marsilio Ficino’s Platonic Theology, Volume II

3We must therefore arrive at last at a judge free from affection. While this judge passes judgment on the body's affections, if it receives from them some bodily quality, it is without doubt acted upon; if it receives no such quality, it is not formed by the body. The judge must therefore be of such a kind that it receives neither affections nor forms from bodies. The soul could not be such a judge if it were itself either an exceedingly subtle body submerged in this body, or some affection of this body, or a point belonging to such an affection. Augustine and Plotinus confirm these Platonic conclusions. It seems to me that when the soul senses within the body, it does not undergo anything from the body but acts with greater attention amid the body's affections. These activities—easy when there is agreement, difficult when there is disagreement—do not escape the soul; and this is the whole of what we call sensing. Yet this sensory capacity, which remains present even when nothing is being sensed, exists through something like a bodily instrument. The soul gives that instrument such a temperament that the sensory power within it is readier to act attentively upon the body's affections, so that it may join like things to like and repel what is harmful. The soul activates, as I suppose, something luminous in the eyes; in the ears, something airy, utterly clear and mobile; in the nostrils, something misty; in the mouth, something moist; and in touch, something earthy and, as it were, muddy. It activates all these quietly so long as the things within the living creature cohere in the unity of health through a certain harmonious consent. But when things are applied that affect the body with a certain otherness, so to speak, the soul performs more attentive activities, fitted to their particular places or instruments, and is then said to sense. Through these activities it gladly associates what is congenial and painfully resists what is uncongenial. When the soul senses, I believe it displays these activities in response to the body's affections; it does not receive those same affections. When the airy spirit of the ear is struck by sound, the soul—which before such an impact animated the bodily organ of hearing in silence—animates that organ with greater attention. To do this is to act, not to be acted upon. The soul that performs the more attentive activity is aware of it, and to be aware of it is to sense. In sum, sensation is either awareness of that more attentive activity or a judgment of bodily affection and quality awakened by the soul's more attentive action.