On the Making of Man

strain to hinder its progress. For just as certain misty vapours are drawn up from the recesses of the earth when it is soaked with rain, whenever the sun heats it with rays of any considerable warmth, so a similar result happens in the earth that is in us, when the nutriment within is heated up by natural warmth; and the vapours, being naturally of upward tendency and airy nature, and aspiring to that which is above them, come to be in the region of the head like smoke penetrating the joints of a wall: then they are dispersed thence by exhalation to the passages of the organs of sense, and by them the senses are of course rendered inactive, giving way to the transit of these vapours. For the eyes are pressed upon by the eyelids when some leaden instrument,52 as it were (I mean such a weight as that I have spoken of), lets down the eyelid upon the eyes; and the hearing, being dulled by these same vapours, as though a door were placed upon the acoustic organs, rests from its natural operation: and such a condition is sleep, when the sense is at rest in the body, and altogether ceases from the operation of its natural motion, so that the digestive processes of nutriment may have free course for transmission by the vapours through each of the passages.

And for this reason, if the apparatus of the organs of sense should be closed and sleep hindered by some occupation, the nervous system, becoming filled with the vapours, is naturally and spontaneously extended so that the part which has had its density increased by the vapours is rarefied by the process of extension, just as those do who squeeze the water out of clothes by vehement wringing: and, seeing that the parts about the pharynx are somewhat circular, and nervous tissue abounds there, whenever there is need for the expulsion from that part of the density of the vapours⁠—since it is impossible that the part which is circular in shape should be separated directly, but only by being distended in the outline of its circumference⁠—for this reason, by checking the breath in a yawn the chin is moved downwards so as to leave a hollow to the uvula, and all the interior parts being arranged in the figure of a circle, that smoky denseness which had been detained in the neighbouring parts is emitted together with the exit of the breath. And often the like may happen even after sleep when any portion of those vapours remains in the region spoken of undigested and unexhaled.

Hence the mind of man clearly proves its claim53 to connection with his nature, itself also cooperating and moving with the nature in its sound and waking state, but remaining unmoved when it is abandoned to sleep, unless anyone supposes that the imagery of dreams is a motion of the mind exercised in sleep. We for our part say that it is only the conscious and sound action of the intellect which we ought to refer to mind; and as to the fantastic nonsense which occurs to us in sleep, we suppose that some appearances of the operations of the mind are accidentally moulded in the less rational part of the soul; for the soul, being by sleep dissociated from the senses, is also of necessity outside the range of the operations of the mind; for it is through the senses that the union of mind with man takes place; therefore when the senses are at rest, the intellect also must needs be inactive; and an evidence of this is the fact that the dreamer often seems to be in absurd and impossible situations, which would not happen if the soul were then guided by reason and intellect.

It seems to me, however, that when the soul is at rest so far as concerns its more excellent faculties (so far, I mean, as concerns the operations of mind and sense), the nutritive part of it alone is operative during sleep, and that some shadows and echoes of those things which happen in our waking moments⁠—of the operations both of sense and of intellect⁠—which are impressed upon it by that part of the soul which is capable of memory, that these, I say, are pictured as chance will have it, some echo of memory still lingering in this division of the soul.

With these, then, the man is beguiled, not led to acquaintance with the things that present themselves by any train of thought, but wandering among confused and inconsequent delusions. But just as in his bodily operations, while each of the parts individually acts in some way according to the power which naturally resides in it, there arises also in the limb that is at rest a state sympathetic with that which is in motion, similarly in the case of the soul, even if one part is at rest and another in motion, the whole is affected in sympathy with the part; for it is not possible that the natural unity should be in any way severed, though one of the faculties included in it is in turn supreme in virtue of its active operation. But as, when men are awake and busy, the mind is supreme, and sense ministers to it, yet the faculty which regulates the body is not dissociated from them (for the mind furnishes the food for its wants, the sense receives what is furnished, and the nutritive faculty of the body appropriates to itself that which is given to it), so in sleep the supremacy of these faculties is in some way reversed in us, and while the less rational becomes supreme, the operation of the other ceases indeed, yet is not absolutely extinguished; but while the nutritive faculty is then busied with digestion during sleep, and keeps all our nature occupied with itself, the faculty of sense is neither entirely severed from it (for