 This has led some commenters to think that Leibniz gave up the account of sufficient reason as an a priori proof. If there were a proof or demonstration, it would reveal that the concept of the predicate was contained in the concept of the subject in a finite number of steps and hence every proposition would be necessary. Leibniz is not a necessitarian in his mature philosophy and thus he could not have accepted this consequence. Instead, he must have shifted from the conception of a sufficient reason as an a priori proof to that of an a priori proof sequence, where the latter notion is understood as an analysis that converges on an identity without reaching it in a finite number of steps (see Sleigh 1983: 200). What it means for an analysis to converge on an identity is, unfortunately, obscure. Nevertheless, there is some clear sense in which every contingent truth has a sufficient reason on this understanding. The sufficient reason why it is true that Caesar crossed the Rubicon, for example, is that the concept crossing the Rubicon is contained in the concept Caesar. The truth of the proposition obtains in virtue of the concepts of the subject and the predicate. Of course, this reason is undiscoverable by any finite human mind because it is buried too deeply in the concept of Caesar. Only God, in his omniscience sees the conceptual connection between them. It is enough for there to be such a connection for there be a sufficient reason.