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

...are by no means subject to external senses and their change, they provide a source for all the commotions and affects of the soul to which we see men of different temperaments subjected in different ways. These faculties of the soul will not be extinguished, even though the body's irritability and sensibility change greatly with the external senses. If ideas have once crept in, the soul continues to combine and compare them; from this association and combination of ideas, other ideas arise, many of which bring to the soul either pleasure or tedium and impel it to multifarious affects and commotions. This power of the soul to excite affects through the combination of ideas is so free from the dominion of the nervous system that it acts with the greatest vehemence at the very time when the entire nervous system seems to be deprived of all sensibility, which, for example, one can often see in a mind seized by the most serious commotions, or in men of more vivid imagination. The better part of the soul's faculties and the constitution of the body do not, in reality, seem to depend upon one another; at least, it cannot be said that the soul is the cause of the diverse constitution of the body, or, which signifies the same thing, the diverse temperament of the body. Hence, I cannot approve of the custom of most writers on temperaments of attributing a certain character of mind to every bodily temperament, or vice versa, and I willingly confess that I have very often found that no property of mind—among those which are attributed to it—is attached to a certain temperament; nor can anything certain be determined in this matter, if I except the way in which men are accustomed to express the affects and commotions of the mind; for every motion of the mind must be considered as a stimulus acting upon the vital forces. But when irritability and sensibility are great, they are affected even by a light stimulus; nothing seems more certain than that one and the same affect of the mind, according to the varying irritability and sensibility of the body, may produce more or less vehement motions and sensations in the body; this, however, does not prevent me from being convinced that there are diverse temperaments of the soul just as there are of the body c.

Since, however, the discussion was first about the temperament of the body, and its primary cause is located in the vital forces proper to a certain man, let us also pursue this path.

If the distinct notion that we can form for ourselves concerning any power consists in the observation and recognition of all its external relations and all the things that it effects d, I consider the subtle inquiry—whether the vital force is some singular matter or a modification of bodies—to be the more superfluous, the more nature has covered this mystery with darkness, and...

c) Flügel, ibid., p. 159.
d) Mendelsohn’s Morning Hours, Vol. I, p. 113.