This is a very pregnant formulation, and its relevance for defining truth is clear: We are free when deciding what the expressions of our language should mean; thereafter, however, when using these expressions to describe the world, we are confronted with the problem of distinguishing between sentences which correspond to facts and those ones which do not, and solving this problem cannot be given by our free decision. (We are not free even in the case that the respective sentences concern mathematical constructions, but here we will turn our attention to the empirical case.)