§31. Proof of the existence of the rational soul. (1) Difference of man from the brutes. (2) Man’s power of objective thought. Thought is to sense as the musician to his instrument. The phenomena of dreams bear this out.
Firstly, then, the rational nature of the soul is strongly confirmed by its difference from irrational creatures. For this is why common use gives them that name, because, namely, the race of mankind is rational. 2. Secondly, it is no ordinary proof, that man alone thinks of things external to himself, and reasons about things not actually present, and exercises reflection, and chooses by judgment the better of alternative reasonings. For the irrational animals see only what is present, and are impelled solely by what meets their eye, even if the consequences to them are injurious, while man is not impelled toward what he sees merely, but judges by thought what he sees with his eyes. Often for example his impulses are mastered by reasoning; and his reasoning is subject to after-reflection. And every one, if he be a friend of truth, perceives that the intelligence of mankind is distinct from the bodily senses. 3. Hence, because it is distinct, it acts as judge of the senses, and while they apprehend their objects, the intelligence distinguishes, recollects, and shews them what is best. For the sole function of the eye is to see, of the ears to hear, of the mouth to taste, of the nostrils to apprehend smells, and of the hands to touch. But what one ought to see and hear, what one ought to touch, taste and smell, is a question beyond the senses, and belonging to the soul and to the intelligence which resides in it. Why, the hand is able to take hold of a sword-blade, and the mouth to taste poison, but neither knows that these are injurious, unless the intellect decide. 4. And the case, to look at it by aid of a simile, is like that of a well-fashioned lyre in the hands of a skilled musician. For as the strings of the lyre have each its proper note, high, low, or intermediate, sharp or otherwise, yet their scale is indistinguishable and their time not to be recognized, without the artist. For then only is the scale manifest and the time right, when he that is holding the lyre strikes the strings and touches each in tune. In like manner, the senses being disposed in the body like a lyre, when the skilled intelligence presides over them, then too the soul distinguishes and knows what it is doing and how it is acting. 5. But this alone is peculiar to mankind, and this is what is rational in the soul of mankind, by means of which it differs from the brutes, and shews that it is truly distinct from what is to be seen in the body. Often, for example, when the body