Frege’s views on identity continue to provoke scholars, and rightly so. In particular his view in Begriffsschrift of 1879, and its relation to his view in ‘Über Sinn und Bedeutung’ of 1892 deserve careful attention. The issues involved have a wider significance than Frege’s specific views on identity in different periods, though these are important enough. They concern also the move from what I call below ‘thin’ semantics, which is exhausted in signs being assigned content, to a ‘thick’ semantics, in (...) which ‘modes of determining their content’, or Sinne are also concerned. (shrink)