Exposition of the Faith

The reasoning part, it should be understood, naturally bears rule over that which is void of reason. For the faculties of the soul are divided into that which has reason, and that which is without reason. Again, of that which is without reason there are two divisions: that which does not listen to reason, that is to say, is disobedient to reason, and that which listens and obeys reason. That which does not listen or obey reason is the vital or pulsating faculty, and the spermatic or generative faculty, and the vegetative or nutritive faculty: to this belong also the faculties of growth and bodily formation. For these are not under the dominion of reason but under that of nature. That which listens to and obeys reason, on the other hand is divided into anger and desire. And the unreasoning part of the soul is called in common the pathetic and the appetitive. Further, it is to be understood, that impulsive movement likewise belongs to the part that is obedient to reason.

The part which does not pay heed to reason includes the nutritive and generative and pulsating faculties: and the name “vegetative” is applied to the faculties of increase and nutriment and generation, and the name “vital” to the faculty of pulsation.

Of the faculty of nutrition, then, there are four forces: an attractive force which attracts nourishment: a retentive force by which nourishment is retained and not suffered to be immediately excreted: an alternative force by which the food is resolved into the humours: and an excretive force, by which the excess of food is excreted into the draught and cast forth.

The forces again, inherent in a living creature are, it should be noted, partly psychical, partly vegetative, partly vital. The psychical forces are concerned with free volition, that is to say, impulsive movement and sensation. Impulsive movement includes change of place and movement of the body as a whole, and phonation and respiration. For it is in our power to perform or refrain from performing these acts. The vegetative and vital forces, however, are quite outside the province of will. The vegetative, moreover, include the faculties of nourishment and growth, and generation, and the vital power is the faculty of pulsation. For these go on energising whether we will it or not.

Lastly, we must observe that of actual things, some are good, and some are bad. A good thing in anticipation constitutes desire: while a good thing in realisation constitutes pleasure. Similarly an evil thing in anticipation begets fear, and in realisation it begets pain. And when we speak of good in this connection we are to be understood to mean both real and apparent good: and, similarly, we mean real and apparent evil.