A system and method to allow a user to engage in a collaborative discourse embedded in messaging platforms such as email or instant messaging, and to visualize the structure of that discourse. The system provides the ability to create and modify tree-like structures, which can represent outlines or tables of contents employed in documents. These structures take the place of traditional documents in representing the work product of a knowledge worker. These structures are related to the discourse in that messages may refer to nodes of these structures, and hence be understood to be related. It is the interplay between the creation of a structured message-based discourse and the persistent outline-form knowledge structures that allows message-based correspondence, including the reading and writing of documents, to be performed with increased efficiency and at a higher level of integration.