xvi SYSTEMATIC THOUGHT 367 



interconnection of facts in all reasoning, and that the 

 distinction is therefore a mere matter of degree. But 

 even in the Third Stage systematisation is an underlying 

 principle, not the explicit object of mental effort. Com- 

 mon sense carries interconnection as far as is necessary for 

 the purpose in hand. But a new step is taken when the 

 purpose in hand is that of making interconnection com- 

 plete, and this is the step taken when we begin to inves- 

 tigate a subject for the sake of understanding it through 

 and through. In science system becomes the explicit 

 purpose. 



Science is systematic in the first place because it seeks 

 to be complete. It takes a certain subject matter and 

 examines it not from the point of view of some practical 

 or imaginative interest, but for the sake of understanding 

 its essential nature as exhibited in all its developments. 

 Thus the beginning of science is the marking off, often by 

 a crude distinction which is afterwards revised, of a 

 department of experience for its field of operations. Next, 

 since the business of science is thorough understanding, it 

 must discover as well as it can the real connections of 

 things. This involves going beneath the generalities of 

 common sense, with their "practical certainty," to the 

 most definite and precise conceptions attainable. For 

 this purpose both terms and their relationships must be 

 accurately defined, and hence the saying a one-sided 

 saying that science is measurement. Hence also the part 

 played by definition, the true place of which is neither at 

 the beginning nor at the end of science, but all along its 

 march the definitions being modified as knowledge of 

 the subject advances. To form some idea of the relation 

 between accuracy and systematic interconnection, we might 

 compare common sense to the implements of a handicraft, 

 and science to a modern machine. The parts of the loco- 

 motive or the printing machine must be adjusted with 

 the minutest accuracy to fit into a scheme of rigid wheels 

 and levers. The craftsman's tool may deviate from the 

 normal, and the craftsman himself will correct the 

 deviations. He gets to know his implement and accommo- 

 dates himself to its individuality. The slightest deviation 



