Chapter Two: On the Sayings of the Ancients

of heat in the natural spirit (al-rūḥ al-ṭabīʿī) is met by no counteracting agent, while it is of recent date; and because its date is recent, the innate heat cannot yet have rendered it subtle. The psychic spirit, on the other hand, is counteracted by its dwelling-place, which is the brain, for the brain is cold; yet the term of heat within it is long, so it became more subtle through the length of that term and the dissolving of what is gross, and colder through the neighbourhood of its place, which is the brain. Out of the brain it diffuses through the rest of the body, and its act is sensation and motion.

Animals share in these spirits, and the physicians did not affirm a further spirit for man, because their aim was to set out that to which health and sickness attach; and if man does have another spirit, its treatment is not of the genus of the medicine of bodies.

As for the soul (nafs), they did not mention it explicitly in medicine, since in medicine they mentioned only the elements, the temperaments (amzijah), the organs, the spirits, the faculties and the acts. So some of them said that the soul must be one of these things: some said the soul is the organs together with the spirits, and is this living frame; a group inclined to its being the balanced temperament; some held that it is the blood; others claimed that it is the humours; a group believed that it is the faculties; and a group said that it is something other than these things, following upon the balanced temperament, coming to be when the temperament is firmly established, making use of the faculties and the instruments, and acquiring objects of desire and perfections — and this is the doctrine of the philosophers.

Gate Two: On the Sayings of the Ancients

As for the spirit, what is understood by it among them is that it is a substance which is neither a body nor bodily, so that the intellects (ʿuqūl) and the souls both fall under it; but it is better to restrict "spirit" to that which has no need of a bodily instrument, so that the spirit is higher than the soul — and it is that to which the philosophers give the name intellect (ʿaql). As for the soul, in the view of all of them it is either celestial or terrestrial, and each of the two divisions is either bodily or immaterial. The bodily is like forms subsisting in the matters of bodies: it is the vegetative soul that is in plants and the animal soul that is in animals; and of the same sort as these souls are the celestial souls in the stars and in the bodies of the heavens, which move them. As for that which is not bodily, the celestial ones among them are souls numbered by the spheres and not, again, by the number of the stars; while the terrestrial one among them is the soul of man, which is what they call the rational soul (al-nafs al-nāṭiqah). They affirmed no terrestrial soul that is neither a body nor subsisting in a body other than this one, save that a number of the later thinkers said that the satans are immaterial terrestrial souls. If that is so, it may be that they mean the satans to be a group of human beings who have reached the utmost in evil and gone to the extreme in harm and injury; or it may be that they mean them to be another species, in which case they would be holding that there are immaterial terrestrial souls of more than one species.

The difference between the soul and the spirit is that the spirit performs its act without depending upon a bodily instrument, whereas the soul does not work except by instruments. For this reason they said that souls do not create bodies but only move them: since their working is by a bodily instrument, how should they have any working upon that without which they have no working at all?

Existents, on their doctrine, fall into five ranks. [Accidents] — these are the basest and lowest of them, and they have existence and subsistence per se, that is, in their existence they do not require a substratum in any respect, unlike whiteness and blackness, which cannot exist except as subsisting in a substratum, which is the body or the substance. Then [the soul], which has existence and subsistence per se