128 STONEY—UNIVERSE OF REAL EXISTENCES. [April 3, 
_ tion under the physical hypothesis that it is they which act, and to 
confine our’ efforts to tracing out what effects this action must be 
supposed capable of producing, and under what laws it must operate, 
in order that it may account for what occurs in nature. 
This, however, is felt by many persons to be too abstract an atti- 
tude of mind; and, to satisfy them, and import into the hypothesis 
the plausibility which they demand, by relieving the fundamental 
conceptions of what is oppressively felt as the absurdity of suppos-’ 
ing that syntheta of perceptions act, it is usual to supplement the 
syntheta by piling an aérial Pelion upon this solid Ossa, and by sup- 
posing that in addition to the sensible object which occupies any por- 
tion of space there is what is called 7¢s material substance occupying 
the same position, which, partly directly and partly by its motions, 
acts on other material substances—the ether being one of these so- 
called swdstances. According to this, which is the prevalent hypoth- 
esis among both scientific and non-scientific men, it is these ‘ sub- 
stances’ which travel about through space ; and the sensible objects, 
which are what we see and feel, are supposed to accompany them 
in their peregrinations by reason of the way in which they, the 
substances, act (usually through intermediate ‘ substances’) upon our 
organs of sense. 
This is the usual point of view: but more careful thinkers will 
do well to eschew this somewhat convenient, but by no means ne- 
cessary, encumbrance upon the unadulterated process of physical 
investigation which treats the sensible objects themselves, the bare 
syntheta of perceptions and ultra-perceptions, as though they were 
what bring about the changes that occur in nature ; and will do well 
to occupy themselves exclusively in tracing out the laws that must, 
under this Ayfothesis, be in operation in order that the effects may 
be what they are. 
This, the true physical hypothesis, is eminently useful and is 
therefore legitimate; but the addition that has been saddled upon 
it, that there are ‘ material substances’ present, is unnecessary, and 
as it is misleading and tends to keep out of view the really ex- 
istent autic universe, it ought to be discarded by all persons who 
‘wish to think clearly. This is the course which all careful think- 
ers should prefer, because it keeps clearly before our minds that in 
the Physical Hypothesis we make use of a hypothesis and not of a 
theory. By being thus careful we avoid the risk of throwing dust 
in our own eyes. It cannot be too distinctly kept in view that the 
