The problems involved with sense and reference differ significantly from those dealt with in the previous chapter. The problems we dealt with there involved questions of logic and logical calculus, which Frege indubitably considered to be ontologically relevant; the problems we are about to discuss are more of an epistemological nature. And it is an epistemological reflection which Frege offers in "On Sense and Reference" where he deals with the essence of equality (identity), which had already been treated in some detail in the Begriffsschrift. Frege"s procedure can be reproduced as follows. If one understands identity as a relation between objects — or, more precisely, of an object to itself — a true judgement of the form "a = b" will express the same relation of identity as a judgement of the form "a = a". The two judgements will not differ in cognitive value, in direct contradiction to the occurrence of judgements of the form "a = b" which are not able to be established a priori like the analytic judgement "a = a".