Plato, Timaeus

When a body has become diseased mainly from an excess of fire, it produces constant inflammations and fevers; when from air, quotidian fevers; when from water, tertian fevers, because that element is more sluggish than air or fire; and when from earth, which is the fourth and most sluggish of the elements and is purged in four-fold periods of time,¹ it causes quartan fevers and is cured with difficulty. [86b]

Such is the manner in which diseases of the body come about; and those of the soul which are due to the condition of the body arise in the following way. We must agree that folly is a disease of the soul²; and of folly there are two kinds, the one of which is madness, the other ignorance. Whatever affection a man suffers from, if it involves either of these conditions it must be termed “disease”; and we must maintain that pleasures and pains in excess are the greatest of the soul's diseases. For when a man is overjoyed or contrariwise suffering excessively [86c] from pain, being in haste to seize on the one and avoid the other beyond measure, he is unable either to see or to hear anything correctly, and he is at such a time distraught and wholly incapable of exercising reason. And whenever a man's seed grows to abundant volume in his marrow,³ as it were a tree that is overladen beyond measure with fruit, he brings on himself time after time many pangs and many pleasures owing to his desires and the issue thereof, and comes to be in a state of madness [86d] for the most part of his life because of those greatest of pleasures and pains, and keeps his soul diseased and senseless by reason of the action of his body. Yet such a man is reputed to be voluntarily wicked and not diseased; although, in truth, this sexual incontinence, which is due for the most part to the abundance and fluidity of one substance because of the porosity of the bones, constitutes a disease of the soul. And indeed almost all those affections which are called by way of reproach “incontinence in pleasure,” as though the wicked acted voluntarily, are wrongly so reproached; for no one is voluntarily wicked,⁴ [86e] but the wicked man becomes wicked by reason of some evil condition of body and unskilled nurture, and these are experiences which are hateful to everyone and involuntary. And again, in respect of pains likewise the soul acquires much evil because of the body.

For whenever the humors which arise from acid and saline phlegms, and all humors that are bitter and bilious wander through the body and find no external vent