Commentary on Human Temperaments as They Depend on the Structure and Fabric of the Body

the vital force/influence in the temperament of the soul exerts the greatest influence, since the sensory organs of the body are rendered fit to receive impressions through that vital power. Nothing exists in the intellect, as the most common theorem holds, which was not previously in the senses; yet from this it cannot be concluded that the entire temperament of the soul depends upon the constitution of the body in such a way that, for example, a cheerful mind inclined toward any kind of pleasure is always joined to the constitution of the body which they call sanguine, as is generally thought. Ambition and anger can fall not only upon the choleric, nor fear only upon the melancholic, but upon a man of any temperament whatsoever, if indeed he lives in those relations that favor such affections of the mind. The reason, however, and the manner in which each one displays the motions of his own mind, is different according to different irritability and sensibility; since each and every affection of the mind excites the actions and motions of the body like a stimulus. From this diverse irritability and sensibility of the body depends the diverse effect of affections in men of diverse temperament.

But let us leave aside individual affections, of which, as it seems to me, there is not a single one that could be ascribed particularly to a certain bodily temperament, and let it please us instead to have a reason for the diversity that I call the temperament of the soul. It consists, indeed, in the diversity of genius, memory, and imagination, which, while depending little on the greater part of the body, is nevertheless proper to every man. In changing these properties of the mind, education, the increase of knowledge, and diverse association with diverse men are indeed most powerful. Nevertheless, not a few phenomena compel us to believe that there are some innate causes present in man, by which the origin of ideas, the power of memory and imagination, the benefit of thinking inherent to each one through the aid of attention, the comparing of ideas, and the forming of judgment are diversely determined, without them admitting any change, with very few exceptions.

§. 12.

The causes of this innate difference in the disposition of the human mind are the following, the number of which would certainly increase further if we knew the intimate organism of the brain and the function of all its parts:

a) The force and efficacy of the nervous system, which is more or less apt for its functions. Since no sensation occurs except through the nerves, and the first ideas of all things are conveyed to the soul solely through the sensory organs, it is also clear that sensations and the primary representations of things depend much on the condition of the nerves. For this reason, we see nervous people, or, as others call them, melancholic people, most inclined to moroseness and sadness; the great sensibility of the nerves, affected by any stimulus whatsoever, opens a way to unpleasant