Knowledge is to be all of the perceptual type, where what is known is directly presented; and, in conformity with this principle, being is to be restricted to the content of the living pulses of experience. [Sidenote: The Refutation of Material Substance.] § 129. Berkeley, then, beginning with the threefold world of Descartes and of common-sense, proposes to apply Locke's theory of knowledge to the discomfiture of corporeal nature. It was a radical doctrine, because it meant for him and for his contemporaries the denial of all finite objects outside the mind. But at the same time it meant a restoration of the homogeneity of experience, the reëstablishment of the qualitative world of every-day living, and so had its basis of appeal to common-sense. The encounter between Hylas, the advocate of the traditional philosophy, and Philonous, who represents the author himself, begins with an exchange of the charge of innovation. _Hyl._ I am glad to find there was nothing in the accounts I heard of you. _Phil._ Pray, what were those? _Hyl._ You were represented, in last night's conversation, as one who maintained the most extravagant opinion that ever entered into the mind of man, to wit, that there is no such thing as _material substance_ in the world. _Phil._ That there is no such thing as what _philosophers_ call _material substance_, I am seriously persuaded: but if I were made to see anything absurd or sceptical in this, I should then have the same reason to renounce this that I imagine I have now to reject the contrary opinion. _Hyl._ What! can anything be more fantastical, more repugnant to Common-Sense, or a more manifest piece of Scepticism, than to believe there is no such thing as _matter_? _Phil._ Softly, good Hylas. What if it should prove that you, who hold there is, are, by virtue of that opinion, a greater sceptic, and maintain more paradoxes and repugnances to Common-Sense, than I who believe no such thing?[276:7] Philonous now proceeds with his case. Beginning by obtaining from Hylas the admission that pleasure and pain are essentially relative and subjective, he argues that sensations such as heat, since they are inseparable from these feelings, must be similarly regarded. And he is about to annex other qualities in turn to this core of subjectivity, when Hylas enters a general demurrer: