 Brouwer gave the intuitionistic conception of mathematics an explicitly subjective twist by introducing the creative subject. The creative subject was conceived as a kind of idealized mathematician for whom time is divided into discrete sequential stages, during each of which he may test various propositions, attempt to construct proofs, and so on. In particular, it can always be determined whether or not at stage \(n\) the creative subject has a proof of a particular mathematical proposition \(p\). While the theory of the creative subject remains controversial, its purely mathematical consequences can be obtained by a simple postulate which is entirely free of subjective and temporal elements.