524 PROFESSOR ALISON ON THE BELIEF 
same suspicious darkness ;—not to interrogate Nature, with a view to the dis- 
covery of truth, but, by a cross-examination of Nature, to involve her in such con- 
tradictions as might set aside the whole of her evidence, as good for nothing.” 
(Phil. Essays, p. 56.) 
The argument of BerkELEY and Hume, although expressed in various terms, 
seems in substance to have been always this,—That we are made acquainted 
with any existence external to ourselves only by means of our own Sensations, 
i. é., of certain acts or states of our own minds; or, as they usually expressed it, 
by ideas in our own minds ; that any such external objects as exist must be the 
exact images or prototypes of these ideas or mental states, and that it is absurd to 
assert that an act or state of mind, whether called sensation or idea, can be the 
exact image or resemblance of any thing but another act of the same, or some 
other mind. 
The following passage from Mr Hume is given by Dr Rem, as the shortest and 
clearest exposition of the argument which he had anywhere found :— 
* The universal and primary opinion of all men, that we perceive external 
objects, is soon destroyed by the slightest Philosophy, which teaches us, that 
nothing can be present to the mind but an image or Perception ;” (the distinction 
of which term from Sensation, was not recognised by Hume), “no man who re- 
flects, ever doubted that the existences which we consider when we say this house, 
and that tree, are nothing but perceptions in the mind, and /leeting copies and re- 
presentations of other existences which remain uniform and independent. So far, 
then, we are necessitated by reasoning to depart from the primary instincts of 
nature, and to embrace a new system with regard to the evidence of our senses.” 
To the same purpose we have the explicit declaration of BERKELEY, “ that the 
existence of bodies, out of a mind perceiving them, is not only impossible, but a 
contradiction of terms.” 
This is not, as Dr Brown stated it, “amere negative assertion, that the 
existence of external things cannot be proved by argument” (vol. ii., p. 55), but 
as Dr Rem had said, a distinct positive assertion, that argument or reasoning does 
compel, or necessitate, our departing from the belief in that existence, as involving 
an absurdity or contradiction. It was these positive but puzzling, and even 
humiliating assertions, and these only, that Dr Rem undertook to confute. 
III. It was quite a misconception to assert, as Dr Brown repeatedly and con- 
fidently did, that the term Ideas, in the language of Hug, or of any philosopher 
after LockE, was to be understood on/y metaphorically or figuratively, as an ex- 
pression for acts or states of mind, and did not imply belief in the existence of 
anything intermediate between the mind and the external objects of sense. 
He shewed, indeed, that the term had been used occasionally in that metapho- 
rical sense by various authors; which Dr Rew knew, and regarded as a proof of its 
