 Twardowski's main publication in the Vienna period is, next to his doctoral dissertation Idea and Perception (1891), his Habilitationsschrift, On the Content and Object of Presentations (1894), Twardowski's most influential work. According to J. N. Findlay, Content and Object is “unquestionably one of the most interesting treatises in the whole range of modern philosophy; it is clear, concentrated, and amazingly rich in ideas” (1963, 8).