_The mere bulk of psychological material would be less formidable if every writer adopted the same principles and wrote from the same point of view; but that is hardly to be expected._ Psychology has always been exposed to the infection of common sense; it has only recently turned to scientific methods; and when the time came for it to take its place among the sciences, there was naturally difference of opinion regarding the standpoint it should assume, the procedure it should follow, the model it should seek to copy. Where such differences of opinion obtain, the best way to begin your study is to =master one system thoroughly=; your ideas are thus made consistent and your knowledge receives an orderly arrangement; then, as you read further, you can use this system as a touch-stone whereby to test new ideas and to arrange new knowledge; and if the new ideas seem preferable to the old, or if the old framework breaks down under the new knowledge, you can alter your own system accordingly. If you begin, on the contrary, by studying a number of works abreast, you are liable to become confused. And it is better to be wrong than to be muddled; for truth, as Bacon said, emerges more quickly from error than from confusion. § 8. =A Personal Word to the Reader.=—These introductory sections are not easy. The only way to make them easy would be, as an Irishman might say, to leave the difficult things out; but then you would come to the later chapters, where we study mental phenomena in the concrete, with all sorts of prepossessions and misunderstandings; psychology would be one long difficulty instead of being, as it henceforth ought to be, a bit of straight sailing.