The main goal of this paper is to reflect on what characterizes the evidence of the propositions that we hold to be necessary. I have tried to show that the evidence of every necessarily true proposition takes the form of a self-contained operational composition. In conclusion, I will point out in what respects the view I defend might help to reconcile some traits of Husserl's understanding of material a priori truth with some of the later Wittgenstein's intuitions concerning linguistic meaning.