Timaeus

But it belongs to a man when in his right mind to recollect and ponder both the things spoken in dream or waking vision by the divining and inspired nature, and all the visionary forms that were seen, and by means of reasoning to discern about them all wherein they are significant and for whom they portend evil or good in the future, the past, or the present. But it is not the task of him who has been in a state of frenzy, and still continues therein, to judge the apparitions and voices seen or uttered by himself; for it was well said of old that to do and to know one’s own and oneself belongs only to him who is sound of mind. Wherefore also it is customary to set the tribe of prophets to pass judgement upon these inspired divinations; and they, indeed, themselves are named diviners by certain who are wholly ignorant of the truth that they are not diviners but interpreters of the mysterious voice and apparition, for whom the most fitting name would be prophets of things divined. For these reasons, then, the nature of the liver is such as we have stated and situated in the region we have described, for the sake of divination. Moreover, when the individual creature is alive this organ affords signs that are fairly manifest, but when deprived of life it becomes blind and the divinations it presents are too much obscured to have any clear significance. The structure of the organ which adjoins it, with its seat on the left, is for the sake of the liver, to keep it always bright and clean, as a wiper that is laid beside a mirror always prepared and ready to hand. Wherefore also, whenever any impurities due to ailments of the body occur round about the liver, the loose texture of the spleen cleanses and absorbs them all, seeing that it is woven of a stuff that is porous and bloodless: hence, when it is filled with the offscourings, the spleen grows to be large and festered; and conversely, when the body is cleansed, it is reduced and shrinks back to its primal state. Concerning the soul, then, what part of it is mortal, what part immortal, and where and with what companions and for what reasons these have been housed apart, only if God concurred could we dare to affirm that our account is true; but that our account is probable we must dare to affirm now, and to affirm still more positively as our inquiry proceeds: affirmed, therefore, let it be. The subject which comes next to this we must investigate on the same lines; and that subject is the way in which the remainder of the body has been generated. Its construction would most fittingly be ascribed to reasoning such as this.