INTRODUCTORY 15 



that the material of science is coextensive with the whole 

 life, physical and mental, of the universe, and furthermore 

 that the limits to our perception of the universe are only- 

 apparent, not real. It is no exaggeration to say that the 

 universe was not the same for our great-grandfathers as it 

 is for us, and that in all probability it will be utterly 

 different for our great-grandchildren. The universe is a 

 variable quantity, which depends upon the keenness and 

 structure of our organs of sense, and upon the fineness of 

 our powers and instruments of observation. We shall see 

 more clearly the important bearing of this latter remark 

 when we come to discuss more closely in another chapter 

 how the universe is largely the construction of each indi- 

 vidual mind. For the present we must briefly consider 

 the former remark, which defines the unlimited scope of 

 science. To say that there are certain fields — for example, 

 metaphysics — from which science is excluded, wherein its 

 methods have no application, is merely to say that the 

 rules of methodical observation and the laws of logical 

 thought do not apply to the facts, if any, which lie within 

 such fields. These fields, if indeed such exist, must lie 

 outside any intelligible definition which can be given of 

 the word knotvledge. If there are facts, and sequences to 

 be observed among those facts, then we have all the 

 requisites of scientific classification and knowledge. If 

 there are no facts, or no sequences to be observed among 

 them, then the possibility of all knowledge disappears. 

 The greatest assumption of everyday life — the inference 

 which the metaphysicians tell us is wholly beyond science 

 — namely, that other beings have consciousness as well as 

 ourselves, seems to have just as much or as little scientific 

 validity as the statement that an earth-grown apple would 

 fall to the ground if carried to the planet of another star. 

 Both are beyond the range of experimental demonstration, 

 but to assume uniformity in the characteristics of brain 

 " matter " under certain conditions seems as scientific as 

 to assume uniformity in the characteristics of stellar 

 " matter." Both are only working hypotheses and valu- 

 able in so far as they simplify our description of the 



