Sensualism is the persistent or excessive pursuit of sensual pleasures and interests In philosophy it refers to the ethical doctrine that feeling is the only criterion for what is good. In epistemology it is a doctrine whereby sensations and perception are the basic and most important form of true cognition. It may oppose abstract ideas. This ideogenetic question was long ago put forward in Greek philosophy (Stoicism, Epicureanism) and further developed to the full by the English Sensualists (John Locke, David Hume) and the English Associationists (Thomas Brown, David Hartley, Joseph Priestley). In the 19th century it was very much taken up by the Positivists (Auguste Comte, Herbert Spencer, Hippolyte Taine, Émile Littré)