304 NATURAL SCIENCE. 



JUNE, 



spatial and temporal relationships. I know no more than Professor 

 Pearson does of the nature of things-in-themselves, or ding-an-siches, 

 or suchlike ; but I do, as man, know somewhat of the world of 

 phenomena, which is, for perception, external to me, and has exten- 

 sion, and in which my clock is ticking in rhythmic sequence ; and I 

 maintain that, for perception, the relationships of these objects are just 

 as much external to me (and just as little^ be it noted, in conceptual 

 analysis) as are the objects themselves. I venture to think, therefore, 

 that to regard space and time as "modes of perception " is, to say 

 the least of it, inconvenient when we are dealing with the field 

 of practical perception. Physics, as a science, is wise, I take it, in 

 dealing with space and time in frankly objective terms, and I think 

 the biologist may still discuss the distribution of organisms in space, 

 and the geologist their distribution in time, without pausing to 

 remind their readers that after all they are only dealing with sense- 

 impressions, and stored sense-impressions, and certain forms of 

 perception. All this may be true enough, but it is out of place either 

 in physics or biology. 



I may here devote a short paragraph to the antinomy, or seeming 

 contradiction, to which we are introduced in this chapter through a 

 consideration of geometrical boundaries and the atomic constitution 

 of matter. In geometry a plane surface is regarded as absolutely 

 continuous : in molecular physics as composed of discontinuous 

 molecules. These views seem to clash. " The conception atom, 

 when applied to our perceptions, is opposed to the conception of 

 surface as the continuous boundary of a body. We have here," 

 says Mr. Pearson, '* an important example of what is not an 

 uncommon occurrence in science, namely, two conceptions which 

 cannot both correspond to realities in the perceptual world. Either 

 perceptual bodies have continuous boundaries, and the atomic theory 

 has no perceptual validity ; or, conversely, bodies have an atomic 

 structure, and geometrical surfaces are perceptually impossible. At 

 first sight this result might appear to the reader to involve a contra- 

 diction between geometry and physics ; it might seem that either 

 physical or geometrical conceptions must be false. But the whole 

 difficulty really lies in the habit we have formed of considering 

 bodies as objective realities, unconditioned by our perceptive faculty." 

 I should myself explain the apparent difficulty in a somewhat 

 different way. Scientific conceptions are general and abstract, and 

 are reached, as Mr. Pearson well points out, by idealising beyond 

 the limits of perceptual experience. Each investigator neglects, or 

 intentionally excludes, such elements of perceptual experience as are 

 disturbing or unnecessary for his special enquiry. He then idealises, 

 or conceives in absolute perfection — a perfection far beyond the limits 

 of experimental verification — the results he obtains. If these 

 different investigators carry this process along different lines, each 

 excluding the element the other is idealising, the results will not 



