This book collects nine seminal essays by Mark Richard published between 1980 and 2014, alongside four new essays and an introduction that puts the essays in context. Each essay is an attempt, in one way or another, to understand the idea of a proposition. Part I discusses whether the objects of thought and assertion can change truth value over time. Part II develops and defends a relativist view of the objects of assertion and thought; it includes discussions of the nature of disagreement, moral relativism, and responds to important objections to relativism. It also explores the idea that thoughts and assertions may be neither true nor false. Part III discusses issues having to do with relations between sentential and propositional structure. Among the topics discussed in Part III are the semantics of quotation, 'mixed quotation', opacity, philosophical analysis and propositional structure, and the semantics of demonstratives and clausal complements.