verse, and not an external universe itself, that he was immediately cognisant of.
The immediate knowledge of an external universe being disproved, its reality was straightway called in question. For the existence of that which is not known immediately, or as it is in itself, requires to be established by an inference of reason. Instead, therefore, of asking, How is the intercourse carried on between man's mind and the external world? the question came to be this, Is there any real external world at all?
Three several systems undertook to answer this question: Hypothetical Realism, which defended the reality of the universe; Idealism, which denied its reality; and Scepticism, which maintained that if there were an external universe, it must be something very different from what it appears to us to be.
Hypothetical Realism was the orthodox creed, and became a great favourite with philosophers. It admitted that an outward world could not be immediately known; that we could be immediately and directly cognisant of nothing but our own subjective states—in other words, of nothing but our perceptions of this outward world; but, at the same time, it held that it must be postulated as a ground whereby to account for these impressions. This system was designed to reconcile common sense with philosophy, but it certainly had not the desired effect. The convictions of common sense repudiated the decrees of so hollow a philosophy. The belief which this sys-
