They are both personal and impersonal. They are abstract terms: they are also the causes of things; and they are even transformed into the demons or spirits by whose help God made the world. And the idea of good (Republic) may without violence be converted into the Supreme Being, who 'because He was good' created all things (Tim.). It would be a mistake to try and reconcile these differing modes of thought. They are not to be regarded seriously as having a distinct meaning. They are parables, prophecies, myths, symbols, revelations, aspirations after an unknown world. They derive their origin from a deep religious and contemplative feeling, and also from an observation of curious mental phenomena. They gather up the elements of the previous philosophies, which they put together in a new form. Their great diversity shows the tentative character of early endeavours to think. They have not yet settled down into a single system. Plato uses them, though he also criticises them; he acknowledges that both he and others are always talking about them, especially about the Idea of Good; and that they are not peculiar to himself (Phaedo; Republic; Soph.). But in his later writings he seems to have laid aside the old forms of them. As he proceeds he makes for himself new modes of expression more akin to the Aristotelian logic. Yet amid all these varieties and incongruities, there is a common meaning or spirit which pervades his writings, both those in which he treats of the ideas and those in which he is silent about them. This is the spirit of idealism, which in the history of philosophy has had many names and taken many forms, and has in a measure influenced those who seemed to be most averse to it. It has often been charged with inconsistency and fancifulness, and yet has had an elevating effect on human nature, and has exercised a wonderful charm and interest over a few spirits who have been lost in the thought of it. It has been banished again and again, but has always returned. It has attempted to leave the earth and soar heavenwards, but soon has found that only in experience could any solid foundation of knowledge be laid. It has degenerated into pantheism, but has again emerged. No other knowledge has given an equal stimulus to the mind. It is the science of sciences, which are also ideas, and under either aspect require to be defined. They can only be thought of in due proportion when conceived in relation to one another. They are the glasses through which the kingdoms of science are seen, but at a distance. All the greatest minds, except when living in an age of reaction against them, have unconsciously fallen under their power.