 Remarks like this suggest that Frege’s view was that propositions are complex entities whose parts are other senses. The proposition is held together in virtue of the fact that at least one of the senses is unsaturated (Frege sometimes also says predicative, or in need of supplementation). Other senses “saturate” or complete the unsaturated senses and in so doing are bound to them to form the proposition/thought. Thus, on this way of interpreting Frege, the mechanism for binding together the constituents of a structured proposition is built right into some of the constituents, (recall that this was true of the view of Zalta [1988] as well).