So various, and if regarded on the surface only, inconsistent, are the statements of Plato respecting the doctrine of ideas. If we attempted to harmonize or to combine them, we should make out of them, not a system, but the caricature of a system. They are the ever-varying expression of Plato's Idealism. The terms used in them are in their substance and general meaning the same, although they seem to be different. They pass from the subject to the object, from earth (diesseits) to heaven (jenseits) without regard to the gulf which later theology and philosophy have made between them. They are also intended to supplement or explain each other. They relate to a subject of which Plato himself would have said that 'he was not confident of the precise form of his own statements, but was strong in the belief that something of the kind was true.' It is the spirit, not the letter, in which they agree--the spirit which places the divine above the human, the spiritual above the material, the one above the many, the mind before the body. The stream of ancient philosophy in the Alexandrian and Roman times widens into a lake or sea, and then disappears underground to reappear after many ages in a distant land. It begins to flow again under new conditions, at first confined between high and narrow banks, but finally spreading over the continent of Europe. It is and is not the same with ancient philosophy. There is a great deal in modern philosophy which is inspired by ancient. There is much in ancient philosophy which was 'born out of due time; and before men were capable of understanding it. To the fathers of modern philosophy, their own thoughts appeared to be new and original, but they carried with them an echo or shadow of the past, coming back by recollection from an elder world. Of this the enquirers of the seventeenth century, who to themselves appeared to be working out independently the enquiry into all truth, were unconscious. They stood in a new relation to theology and natural philosophy, and for a time maintained towards both an attitude of reserve and separation. Yet the similarities between modern and ancient thought are greater far than the differences. All philosophy, even that part of it which is said to be based upon experience, is really ideal; and ideas are not only derived from facts, but they are also prior to them and extend far beyond them, just as the mind is prior to the senses. Early Greek speculation culminates in the ideas of Plato, or rather in the single idea of good. His followers, and perhaps he himself, having arrived at this elevation, instead of going forwards went backwards from philosophy to psychology, from ideas to numbers. But what we perceive to be the real meaning of them, an explanation of the nature and origin of knowledge, will always continue to be one of the first problems of philosophy.