(ii) Joining the set. Membership of the set of Mathematicians results from an extended period of training (to acquire the necessary knowledge and skills) followed by participation in the institutions of mathematics, and presumably the adoption of (at least some) of the values of the mathematics community (Davis and Hersh, 1980,Tymoczko, 1985). The training requires interaction with other mathematicians, and with information technology artefacts (books, papers, software, etc.). Over a period of time this results in personal knowledge of mathematics. To the extent that it exists, the shared knowledge of mathematics results from this period of training in which students are indoctrinated with a ‘standard’ body of mathematical knowledge. This is achieved through common learning experiences and the use of key texts, which have included Euclid, Van der Waerden, Bourbaki, Birkhoff and MacLane, and Rudin, in the past. Many, probably most students fall away during this process. Those that remain have successfully learned part of the official body of mathematical knowledge and have been ‘socialized’ into mathematics. The is a necessary, but not sufficient condition for entry into the set of mathematicians (with a membership value significantly greater than 0). The ‘standard’ body of knowledge will have a shared basis, but will vary according to which subfields the mathematician contributes.