26o THE GRAMMAR OF SCIENCE 



shown to be ether in motion. In other words, it is well 

 within the range of possibility that during the next quarter 

 of a century science will have discovered that our symbolic 

 description of the phenomenal universe will be immensely 

 simplified, if we take as our symbolic basis for material 

 groups of sense-impressions a type of motion of the con- 

 ceptual ether ; in other, more expressive if less accurate, 

 language, if we treat our friends' matter as their non- 

 matter in motion. We shall then find that our sense- 

 impressions of hardness, weight, colour, temperature, 

 cohesion, and chemical constitution, may all be described 

 by aid of the motions of a single medium, which itself is 

 conceived to have no hardness, weight, colour, temperature, 

 nor indeed elasticity of the ordinary perceptual type. 

 This would mean an immeasurably great advance in our 

 scientific power of description. Yet if physicists even 

 then persist in projecting the conceptual into the sphere of 

 sense-impression, and in asserting a phenomenal existence 

 for the ether, we should still be ignorant of what it is that 

 moves, of what ether-matter may really consist in. 



Our analysis, therefore, of the various statements made 

 by physicists and common-sense philosophers with regard 

 to the nature of matter shows us that they are one and 

 all metaphysical — that is, they attempt to describe some- 

 thing beyond sense -impression, beyond perception, and 

 appear, therefore, at best as dogmas, at worst as incon- 

 sistencies. If we confine ourselves to the field of logical 

 inference, we see in the phenomenal universe, not matter 

 in motion, but sense-impressions and changes of sense- 

 impressions, coexistence and sequence, correlation and 

 routine. This world of sense-impression science symbolises 

 in conception by an infinitely extended medium, whose 

 various types of motion correspond to diverse groups of 

 sense-impressions, and enable us to describe the correlations 

 and sequences of these groups. The moving elements of 

 this medium can in thought be conceived of only as 

 geometrical ideals, as points or continuous surfaces. To 

 make our symbolic chart or picture agree the better with 

 perceptual experience, we find it necessary to endow these 



