Born in Grenoble, and originally trained for the priesthood, Condillac became one of the leading followers and interpreters of the empiricist philosophy of Locke, and of the scientific revolution of Newton (it is said that although he wore a cassock until the end of his life, he celebrated Mass only once). His Essai sur l’origine des connaissances humaines (1746, trs. as An Essay on the Origin of Human Knowledge, 1756) was followed by the Traité des sensations (1754, trs. in Philosophical Writings, 1982) which attempted to answer the charge of subjective idealism brought against him by Diderot. In it, Condillac develops an early phenomenology of exterior perception, showing how sensation is not an inert presence, but part of an active involvement with the external world. It is through the development of kinaesthetic and tactile sensation, and the sensations of pressure and physical opposition, that the concept of an external world arises. The sensation of touch is the teacher of the other senses.