"Look you, Hylas, when I speak of Objects, as existing in the Mind, or imprinted on the Senses; I wou'd not be understood in the gross, literal Sense, as when Bodies are said to exist in a place, or a Seal to make an Impression upon Wax."
— Berkeley, George (1685-1753)
Explain to me now, O Philonous! how it is possible, there shou'd be room for all those Trees and Houses to exist in your Mind. Can extended Things be contained in that which is unextended? Or, are we to imagine Impressions made on a Thing void of all Solidity? You cannot say, Objects are in your Mind, as Books in your Study: Or, that Things are imprinted on it, as the Figure of a Seal upon Wax. In what Sense, therefore, are we to understand those Expressions? Explain me this if you can: And I shall then be able to answer all those Queries you formerly put to me, about my Substratum.
Look you, Hylas, when I speak of Objects, as existing in the Mind, or imprinted on the Senses; I wou'd not be understood in the gross, literal Sense, as when Bodies are said to exist in a place, or a Seal to make an Impression upon Wax. My Meaning is only, that the Mind comprehends, or perceives them; and that it is affected from without, or by some Being distinct from itself. This is my Explication of your Difficulty; and, how it can serve to make your Tenent of an unperceiving, material Substratum intelligible, I wou'd fain know.
Nay, if that be all, I confess, I do not see what Use can be made of it. But, are you not guilty of some Abuse of Language in this?
None at all: It is no more than common Custom, which, you know, is the Rule of Language, has authorized: Nothing being more usual, than for Philosophers to speak of the immediate Objects of the Understanding, as Things existing in the Mind. Nor is there any thing in this, but what is conformable to the general Analogy of Language; most part of the mental Operations being signified by Words borrowed from sensible Things; as is plain, in the Terms Comprehend, Reflect, Discourse, &c. which, being applied to the Mind, must not be taken in their gross, original Sense.
(pp. 141-2; cf. ii, 241 in Works)
See Three Dialogues Between Hylas and Philonous: The Design of Which Is Plainly to Demonstrate the Reality and Perfection of Human Knowledge, the Incorporeal Nature of the Soul, and the Immediate Providence of a Deity: In Opposition to Sceptics and Atheists. Also to Open a Method for Rendering the Sciences More Easy, Useful, and Compendious. (London: Printed by G. James, for Henry Clements, at the Half-Moon, in S. Paulâ€™s Church-Yard, 1713). <Link to ESTC><Link to ECCO-TCP>
Working with the Past Masters electronic version of The Works of George Berkeley, ed. T. E. Jessop and A. A. Luce, vol. II (Desirée Park: Thomas Nelson, 1979).