184 GENERAL CONDITIONS OF SCIENTIFIC RESEARCH. 



a preordained manner. Those subjects which are depen- 

 dent for their development upon the previous development 

 of certain others, will have to follow and advance with 

 them. 



We know that the following order of the simple 

 sciences, viz., logic, mathematics, geometry, mechanics, 

 light and heat, electricity and magnetism, chemical affi- 

 nity, &c., is approximately that in which each succeeding 

 science is of a more complex character than the preceding 

 one, and is based upon it. Thus logic treats of existences, 

 but not of their quantities, and in all the succeeding 

 sciences our reasoning must be conducted according to 

 logical rules. The science of mathematics adds to the idea 

 of simple existence the general notions of number and 

 magnitude, and the phenomena of all the sciences which 

 follow it may be quantitatively considered. Geometry (a 

 branch of mathematics) introduces the additional con- 

 ditions of space and direction, and all physical, chemical, 

 and vital phenomena must (as far as we know) 

 exist in space. In the science of mechanics are super- 

 added the ideas and conditions of matter and motion ; 

 and we first obtain by it the notion of force, both static 

 and dynamic. The various active physical powers, includ- 

 ing chemical affinity, are also generally believed to consist 

 of different modes of motion of the molecules of matter, 

 and, if so, depend upon geometrical and mechanical condi- 

 tions. We know also that the mechanical principle, that 

 action and reaction are equal and contrary, pervades all 

 the following sciences, and rules the various actions of the 

 forces of physics and chemistry ; the physical forces also, 

 like mechanical action, take the path of least resistance ; 

 also the motion of the molecules in the phenomena of 

 sound is considered to be vibratory, of light and heat un- 

 dulatory, and of magnetism rotary. None of the phenomena 



