Those who have quarrelled with philosophy for these or other reasons will do well to lay their prejudices aside when they start a study of Eucken, for though he has some of the faults of his class, he has many striking and exceptional excellences. Philosophers in general set out to solve the riddle of the universe. They differ in their statement of the problem, in the purpose of the attempt, and in their methods of attempting the solution. Some will wonder how this marvellous universe ever came into existence, and will consider the question of the existence of things to be the problem of philosophy. Others in observing the diversity of things in the universe wonder what is behind it all; they seek to go beyond mere appearances, and to investigate the nature of that behind the appearances, which they call the reality. In their attempts to solve one or both of these problems, thinkers are led to marvel how it is that we get to know things at all; they are tempted to investigate the possibility of knowledge, and are in this way side-tracked from the main problem. Others in their investigations are struck with amazement at the intricate organisation of the human mind; they leave the riddle of the universe to study the processes of human thought, and examine as far as they are able the phenomena of consciousness. Then thought itself claims the attention of other philosophers; they seek to find what are the laws of valid thought, what rules must be followed in order that through reasoning we may arrive at correct conclusions. Others become attracted to an investigation of the good in the universe, and their question changes from "What is?" to "What ought to be?" Others interest themselves in the problem of the beautiful, and endeavour to determine the essence of the beautiful and of its appreciation. In this way the subject of philosophy separates out into a number of branches. The study of the beautiful is called Æsthetics; of the good, Ethics; of the laws of thought, Logic; of the mind processes, Psychology; of the possibility of knowledge, the Theory of knowledge; while the deeper problems of the existence of things, of reality and unity in the universe, are generally included under Metaphysics. It need hardly be pointed out that all these branches are very closely related, and that a discussion of any one of them involves to some extent a reference to the others. One cannot, for example, attempt to solve the great question of reality without touching upon the possibility of knowledge, without some reference to the processes of the human mind, and the standards of the validity of thought, of the good, and of the beautiful.