"We cannot know whether the gods exist or do not exist; the matter is too obscure, and man's life too short. If they exist, it must be in some manner peculiar to themselves, for we cannot find any trace of their presence in the world. They are not present to us as objects to be perceived by the senses; if they move among us at all it is by stealth, and without leaving so much trace as a ship leaves upon the waves. But man has always believed that they are close to him, and has come to imagine them as haunting every green corner of the earth, each well, and wood, and hill, the blue depths of the sea and the wide regions of the air. We have a God to preside at our sowing and at our harvest, at our setting-forth and at our home-coming; there are gods of flocks and herds, of vineyards and olive groves, of rivers and of the sea. Poetry has peopled the air with them, and given to Aphrodite a team of sparrows, and to Hera a team of peacocks, and to grey-eyed Athene an owl. Indeed, it is strange, so familiar and frequent are they in our thoughts, that we should ever question their existence; yet the moment we seek for any tangible evidence of their presence in the world we are at fault, and the more we consider them the more shadowy and elusive they become. The whole notion of divinity is constantly changing in our minds, adapting itself to new conditions of life, varying its form as our knowledge becomes deeper; but always becoming more spiritual, less tangible, until it seems to be nothing but that wandering breath which quickens all things into life. "At first we imagined the gods as the incarnation of some natural force, like Aphrodite, the foam-born, whom all living creatures obey; or Demeter, the Earth-mother, who produces all the fruits and harvests, and the grass and flowers of the field. Stripped of the mystery and beauty with which the poets have clothed them, these are but the conditions of man's life, his begetting and sustenance; we must seek behind them for that idea of the supreme reason, who is not only the cause but the end of all things, not only the source of existence but the principle from which spring our notions of truth, of wisdom, of justice, and all those ideals which reconcile us to life and bid us hope in the ultimate realisation of the good. It is not sufficient for us to find a cause from which existence is derived, for even if that were laid bare to us we could not find in it our ultimate satisfaction, unless it conformed to the idea of divinity, which, as Socrates and Euripides have agreed, is exclusive of all elements of evil. Is it possible to have this knowledge? There are two insuperable difficulties.