_Further Distinction._--Of these latter, again, some hold the idea which we have of an external world to be merely a state or modification of the mind itself; others regard it as a sort of intermediate connecting link between mind and matter. The former may be called egoistic, and the latter non-egoistic.
_Summary of Classes._--We have then these three great classes--the _Natural Realists_, the _Absolute Idealists_, and the _Representative Idealists_ comprising the Egoistic and Non-Egoistic divisions.
_Distinguished Writers of the different Classes._--On the roll of absolute idealism are names of no small distinction: Berkley and Hume, in England, Fichte and Hegel, in Germany, are of the number; while among the representative idealists one finds Descartes, Arnauld, Malebranche, Leibnitz, Locke, in fine, the greater number of philosophic writers from Descartes onward to the time of Reid. Subsequently even, we find a writer of no less repute than Dr. Brown assuming, as the basis of his philosophy of perception, the exploded theory of representative idealism, under the egoistic form. Of natural realists since the time of Reid, Sir W. Hamilton is the most distinguished.
_Origin of Representative Idealism._--The doctrine of representative perception doubtless originated in the difficulty of conceiving how a purely spiritual existence, the human mind, can, by any possibility, take cognizance of, or be affected by, a purely material substance, the external world. The soul seated in its presence-chamber, the brain, can cognize nothing beyond and without, for nothing can get except where it is present. It must be, then, said the philosophers, that in order to the mind's perceiving any thing of that which lies beyond and without its own immediate locality, there must come to the mind from that outer world certain little images bearing some resemblance to the things without, and _representing_ to the soul that external world. These images--more refined than matter, less spiritual than mind itself, of an intermediate nature between the two--they termed ideas.
_Tendency of Representative to Absolute Idealism._--It is easy to see how such a doctrine would lead almost inevitably to _absolute idealism_. If we do not in perception take cognizance directly of matter external, but only of certain images or ideas in our own minds, then how do we know that these images _correctly represent_ the external reality, which we have never cognized, and never shall? How do we know, in fact, that there _is_ any such external reality? What evidence have we, in a word, of the existence of any thing beyond and without our own minds? This was the actual result to which Berkley and Hume drove the then prevalent philosophy of Europe, as to a legitimate and inevitable result.