Foster's "Essays" were published in 1805. They originated in conversations with Maria Snooke, whom he had first met at Battersea, and who later became his wife, and were addressed to her. An introductory letter, dated "Near Bristol, 30 Aug. 1804", mentions reasons for writing them. The book contained four essays: "On a Man's Writing Memoirs of Himself", "On Decision of Character", "On the Application of the Epithet Romantic", and "On Some of the Causes by which Evangelical Religion has been rendered less acceptable to Persons of Cultivated Taste". In about four months a second edition was called for, and a third was published in 1806.