202 GENERAL CONDITIONS OF SCIENTIFIC RESEARCH. 



small, amount of disturbance or deflection still remained, 

 which could only be acounted for by the supposition 

 of some other and unknown body. That body was 

 at once sought for by the aid of the telescope, and soon 

 afterwards discovered, and proved to be the planet which 

 we now call Neptune. Various other instances might be 

 given of the discovery of new and important phenomena 

 by means of residual differences, especially in the science 

 of astronomy. Residual differences which cannot be- 

 accounted for by known laws or principles are especially 

 important, because their explanation requires a new law or 

 principle. The explanation of residual phenomena in a 

 concrete science sometimes leads to the discovery of new 

 facts and principles in the simple sciences. 



CHAPTER XXII. 



FUNDAMENTAL IMPORTANCE OF QUALITATIVE KNOWLEDGE. 



THE whole of the truths of science may be conveniently 

 viewed as being of two classes, viz., those of simple exist- 

 ence, or qualitative truths, and those of a quantitative 

 character. The greatest facts in science are those of 

 the simplest existence of time and space ; time is the 

 unavoidable condition of all material existence whether 

 qualitative or quantitative, of all thought and action, 

 of all statical and dynamical phenomena, of the opera- 

 tion of all scientific laws and principles, and of the 

 action of all forces and substances. Next in importance 

 is space. Without it no material substance can exist, 

 no physical action occur, and no experiment be made. 

 As all things are evolved in apparently infinite time 

 and boundless space, those two conditions are the womb 



