g6 THE GRAMMAR OF SCIENCE 



the physicist are sicpersensuous, that is, they do not at 

 present represent direct sense-impressions ; but the reader 

 must be careful not to confuse this kind of supersensuous- 

 ness with that of the metaphysician. The physicist looks 

 upon the atom in one or other of two different ways : 

 either the atom is real, that is, capable of being a direct 

 sense-impression, or else it is ideal, that is, a purely 

 mental conception by aid of which we are enabled to 

 formulate natural laws.^ It is either a product of the 

 perceptive faculty, or of the reflective or reasoning faculty 

 in man. It may pass from the latter to the former, from 

 the ideal stage to the real ; but till it does so, it remains 

 merely a conceptual basis for classifying sense-impressions, 

 it is not an actuality. On the other hand, the meta- 

 physician asserts an existence for the supersensuous which 

 is unconditioned by the perceptive or reflective faculties 

 in man. His supersensuous is at once incapable of being 

 a sense-impression, and yet has a real existence apart from 

 the imagination of men. It is needless to say that such 

 an existence involves an unproven and undemonstrable 

 dogma. Nevertheless, the magnitude of the gulf between 

 the supersensuous of the physicist and that of the meta- 

 physician is frequently neglected, and we are told that it 

 is as logical to discuss " things-in-themselves " as molecules 

 and atoms ! 



§ I O. — Progress in the Formulating of Natural Law 



By the formation of conceptions, which may or may 

 not have perceptual equivalents in the sphere of sense- 

 impression, the scientist is able to classify and compare 

 phenomena. From their classification he passes to 

 formulae or scientific laws describing their sequences and 

 relationships. The wider the range of phenomena em- 

 braced, and the simpler the statement of the law, the 

 more nearly we consider that he has reached a " funda- 

 mental law of nature." The progress of science lies in the 

 continual discovery of more and more comprehensive 



1 That is, it is part of a physicist's mental shorthand. 



