“Socrates: Would not he who is fitted to be a guardian, besides the spirited nature, need to have the qualities of a philosopher? Glaucon: I do not apprehend your meaning. S: The trait of which I am speaking, I replied, may be also seen in the dog, and is remarkable in the animal. G: What trait? S: Why, a dog, whenever he sees a stranger, is angry; when an acquaintance, he welcomes him, although the one has never done him any harm, nor the other any good. Did this never strike you as curious? G: The matter never struck me before; but I quite recognize the truth of your remark. S: And surely this instinct of the dog is very charming; —your dog is a true philosopher. G: Why? S: Why, because he distinguishes the face of a friend and of an enemy only by the criterion of knowing and not knowing. And must not an animal be a lover of learning who determines what he likes and dislikes by the test of knowledge and ignorance? G: Most assuredly. S: And is not the love of learning the love of wisdom, which is philosophy?”