This in the Protreptics is the 24th Symbol; but instead of _wear_, it is there _inscribe_. But Iamblichus’ explanation of it is as follows: “This Symbol conformably to the foregoing conception, employs the following exhortation: Philosophize, and before every thing consider the Gods as having an incorporeal subsistence. For this is the most principal root of the Pythagoric dogmas, from which nearly all of them are suspended, and by which they are strengthened even to the end. Do not therefore think that the Gods use such forms as are corporeal, or that they are received by a material subject, and by body as a material bond, like other animals. But the engravings in rings exhibit the bond which subsists through the ring, its corporeal nature and sensible form, and the view as it were of some partial animal, which becomes apparent through the engraving; from which especially we should separate the genus of the Gods, as being eternal and intelligible, and always subsisting according to the same and in a similar manner, as we have particularly, most fully, and scientifically shown in our treatise concerning the Gods.”[97] P. 61. _Nor is it proper to sacrifice a white cock; for this also is a suppliant, and is sacred to the moon._ In the Protreptics, the 18th Symbol is partly the same with, and partly different from this. For it is, “Nourish a cock; but sacrifice it not; for it is sacred to the sun and the moon.” And Iamblichus explains it as follows: “This Symbol advises us to nourish and strengthen the body and not neglect it, dissolving and destroying the mighty tokens of the union, connexion, sympathy, and consent of the world. So that it exhorts us to engage in the contemplation and philosophy of the universe. For though the truth concerning the universe is naturally occult, and sufficiently difficult of investigation, it must, however, at the same time, be inquired into and investigated by man, and especially through philosophy. For it is truly impossible to be discovered through any other pursuit. But philosophy receiving certain sparks, and as it were viatica, from nature, excites and expands them into magnitude, rendering them more conspicuous through the disciplines which it possesses. Hence, therefore, we should philosophize.” P. 61. _It is proper to sacrifice, and to enter temples, unshod._