The question of truth is recurrent in Fregean texts. This work focuses on the historical and theoretical research on the subject in the work of Frege and of those who set out to comment on the matter. The epistemology is handled directly in the article The Thought (1918-1919) that will guide our search for the right way that we know the world. Frege's life will be addressed to clarify the reading of the article as a project that is in the overall work of the philosopher and not separated from the Fregean project, as well as the influences that other philosophers had on the work. The delimitation of what is studied by logic is essential to contextualize how the term 'truht' is actually approached, in the other words, the delimitation...