In the introduction to the Grundlagen, Frege tells us that it is one of the fun- damental principles of his theory of knowledge "always to separate sharply the psychological from the logical, the subjective from the objective" (1884, p. x). This methodological maxim was intended to produce a division of labour between the philosopher and the psychologist, and to clear the ground for the distinctively analytic approach to philosophy. For Frege believed that we could study thoughts independently of thinkers, and that we could map out the logical relations among thought-contents in a wholly objective way that would purge philosophy of any empirical taint. By this method the ideals of analytic philosophy were established: "rigour of proof, precise delimitation of extent of validity, and as a means to this, sharp definition of concepts". (1884, p. 1)