PRIMARY CONCEPTS OF MODERN SCIENCE. 225 



dently of all other objects, and which are supposed to be representable 

 in the sensations of the human eye. The notion of such properties is a 

 contradiction in itself. They cannot possibly exist, and therefore we 

 cannot expect to find any coincidence of our sensations of color with 

 qualities of light." 



The fundamental truth which is implied in these sentences is of such 

 transcendent importance that it is hardly possible to be too emphatic 

 in its statement, or too profuse in its illustration. All quality is rela- 

 tion ; all action is reaction ; all force is antagonism ; all measure is a 

 ratio between terms neither of which is absolute ; every objectively 

 real thing is a term in numberless series of mutual implications, and 

 its reality outside of these series is utterly inconceivable. A material 

 entity, absolute in any of its aspects, would be nothing less than a 

 finite infinitude. There is no absolute material quality, no absolute 

 material substance, no absolute physical unit, no absolutely simple 

 physical entity, no absolute constant, no absolute standard either of 

 quantity or quality, no absolute motion, no absolute rest, no absolute 

 time, no absolute space. There is no physical thing, nor is there a 

 real or conceptual element of such a thing, which is either its own sup- 

 port or its own measure, and which abides either quantitatively, or 

 qualitatively, otherwise than in perpetual change, in an unceasing flow 

 of mutations. An object is large only as compared with another which, 

 as a term of this comparison, is small, but which, as a term in a com- 

 parison with a third object, may be indefinitely large ; and the com- 

 parison which determines the magnitude of objects is between its terms 

 alone, and not between any or all of these terms, and an absolute 

 standard. An object is hard as compared with another which is soft, 

 but which, in turn, may be contrasted with a third still softer; and, 

 again, there is no standard object which is either absolutely hard or 

 absolutely soft. A body is simple as compared with the compound 

 into which it enters as a constituent ; but there is, and can be no physi- 

 cally real thing which is absolutely simple. Similarly, all changes of 

 position or distance between two bodies are wholly relative, and it is 

 a matter of purely arbitrary determination, which of them is taken as 

 being at rest, and which as in motion. It is equally true to say that 

 the earth falls toward the apple, and that the apple falls toward the 

 earth. 



I may observe, in this connection, that not only the law of causality, 

 the persistence of force, and the indestructibility of matter, have their 

 root in the relativity of all objective reality — being, indeed, simply 

 different aspects of this relativity — but that Newton's first and third 

 laws of motion, as well as all laws of least action, so called, in me- 

 chanics (including Gauss's law of movement under least coercion), are 

 but corollaries from the same principle. And the fact that every thing 

 is, in its manifest existence, but a group of relations and reactions, at 

 once accounts for Nature's inherent teleology. 



VOL. IV. — ]5 



