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rjuly, 
ANALYSES OF BOOKS. 
Illusions: a Psychological Study. By James Sully. London : 
C. Kegan Paul and Co. 
To recognise illusions, to understand their origin, and to avoid 
them, is the part of the wise man, just as their unscrutinising 
acceptance is the task of the fool, and their propagation that of 
the quack and the knave. Hence the work before us should have 
an exceedingly wide interest. The author tells us that at bottom 
illusion becomes identified with fallacious inference. He says, 
too truthfully, that “ our luminous circle of rational perception is 
surrounded by a misty penumbra of illusion.*’ It must not, how- 
ever, be supposed that Mr. Sully is one of those who, in language 
common to ultra-sceptical philosophers and to ultra-devout hymn- 
wrights, proclaim — 
“ This world is all a fleeting show 
For man’s illusion given.” 
Whilst declaring that we have “ found a large field for illusory 
cognition in sense-perception, in the introspection of the mind’s 
own feelings, in the reading of other’s feelings, and finally in 
belief,” he holds that illusion has its limits. He admits that 
“ our intuitions of external realities, our indestructible belief in 
the uniformity of Nature, in the nexus of cause and effeCt are at 
least partially true, — true in relation to certain features of our 
common experience. At the worst they can only be called illusory 
as slightly misrepresenting the exaCt results of this experience. 
And so in full view of the subtleties of philosophic speculation, 
the man of science may still feel justified in regarding his 
standard of truth, a stable concensus of belief as above sus- 
picion.” 
Mr. Sully classifies illusions according to their origin, obtaining 
four classes corresponding with four forms of cognition. Thus 
we have illusions of external perception, of internal perception, 
of memory, and of belief. 
We shall turn our attention, in the first place, to the illusions 
of memory. The author distinguishes, as something quite apart 
from mere forgetfulness or from imperfeCl remembrance, three 
classes of illusions. “ We may have false recollections, to which 
there correspond no real events of personal history ; others which 
misrepresent the manner of happening of the events, and others 
