Searle's early work, which did a great deal to establish his reputation, was on speech acts. He attempted to synthesize ideas from many colleaguesincluding J. L. Austin (the "illocutionary act", from "How To Do Things with Words"), Ludwig Wittgenstein and G.C.J. Midgley (the distinction between regulative and constitutive rules)with his own thesis that such acts are constituted by the rules of language. He also drew on the work of Paul Grice (the analysis of meaning as an attempt at being understood), Hare and Stenius (the distinction, concerning meaning, between illocutionary force and propositional content), P. F. Strawson, John Rawls and William Alston, who maintained that sentence meaning consists in sets of regulative rules requiring the speaker to perform the illocutionary act indicated by the sentence and that such acts involve the utterance of a sentence which (a) indicates that one performs the act; (b) means what one says; and (c) addresses an audience in the vicinity.