Three Dialogues Between Hylas and Philonous is a 1713 philosophical work by George Berkeley, written as a dialogue in which the characters discuss the metaphysical ideas which Berkeley had previously propounded to some criticism in A Treatise Concerning the Principles of Human Knowledge.
The two characters are given Greek names which reflect their respective commitments. Hylas is named after the Greek word for matter and takes a materialist position. Philonous, 'lover of mind', defends an idealist stance which is largely Berkeley's own.
Free online texts
Early Modern Texts: Three Dialogues Between Hylas and Philonous, adapted and translated into modern English, by Jonathan Bennett. PDF format.
Gutenberg: Three Dialogues Between Hylas and Philonous. Multiple formats.
Internet Archive: Three Dialogues Between Hylas and Philonous (1901). Multiple formats.
Wikisource: Three Dialogues between Hylas and Philonous. HTML and other formats.
BBC Radio 4 In Our Time: Bishop Berkeley. Peter Millican, Tom Stoneham and Michela Massimi.
Stanford Encyclopedia of Philosophy: George Berkeley.
Further reading at Tom's Learning Notes