is

oi

254 An Essay on the

cumstance. mechanically. When a thingreckoned an illusion, it is the provincephilosophy to find out how the illusion coube effected: in Opticks , when the placethe object is changed, and the dimensionsit enlarged si this is apparent only not real, ^may be reckoned an illusion: yet it is se&and useful knowledge to understand the ^fhow this is produced. And secondly , sincemanner of communicating a things is indep e j^dent on the thing communicated; this canno objection against the manner of corns^ideating this knowledge, let it be as false ^delusive as it will. If I am so affected 1sleep, as to know a man and his desi$ r ' S ’though he hath no existence but in vif^'might not I be so affected as to know *

ft

th * 1

man and his designs, if he had a

istence ? There is all the parity here

needs be desired, to make an inference. _ ^sides, other real and true knowledge,which no exception could be made,be communicated to us the same way. ^subjeB imagined to be read out of the bc>oin the instance above, may be of the 1kind with any of those arguments thatenquired after by men at other times.