95 
speaking, is therefore not an effect of the motion of the sensorium, but a con- 
comitant of it. 
While holding that none of these speculations can be seriously 
regarded as anything but a more or less convenient working hypo- 
thesis, he himself inclines to the second, which he calls the 
“simplest ;” the “simplicity” of which, however, to some minds 
may appear as consisting only in that of a statement which conceals 
an hiatus that cannot be filled up by human intelligence. 
I may perhaps most fitly bring my remarks to a conclusion by 
quoting a sentence from the Introduction to a book which has 
attracted a great deal of notice—“‘ The Unseen Universe ;’—the 
opinion expressed in which appears to me worthy of the most 
attentive consideration: “ We are entire believers,” say the writers 
of this book, “‘in the zujinite depth of Nature, and hold that just as 
we must imagine space and duration to be infinite, so must we 
imagine the structural complexity of the universe to be infinite 
also.” 
