In this paper I try to show that various attempts to solve mysteries concerning intentional objects, so-called the Brentano Puzzle, have driven contemporary philosophy. Especially the origins of phenomenology and analytic philosophy are connected directly or indirectly with the Puzzle, and this means that two chief trends of contemporary philosophy have a common origin. This fact has been overlooked by some philosophers committed to only one of two. To remind them of it, I firstly overviewed history of concepts associated the Brentano Puzzle, in particular, intentio of the Middle Ages and Satz an sich of Bolzano, then analyzed key concepts employed to solve the Puzzle by Frege, Twardowski, Meinong, and Husserl: Gedanke, Inhalt, Nicht-Existenz, and Noema respectively, to speak more commonly, meaning or content. Contemporary analytic philosophies of language, thought, and mind have concentrated on the factors that determine content, and their methodologies was characterized by antagonism, compromise, and harmony between Russell’s semantic Cartesianism and Frege’s Sinn-Bedeutug dualism. According to Kripke and Putnam, determinants of content consist in not only the inside of body, say nerve net, but also the outside world, context. By dint of these external determinants such as causal-informational chains, contents have social character.