 In 1893, he published the first volume of the technical work previously mentioned, Grundgesetze der Arithmetik.  In 1896, he was promoted to ordentlicher Honorarprofessor (regular honorary professor).  Six years later (on June 16, 1902), as he was preparing the proofs of the second volume of the Grundgesetze, he received a letter from Bertrand Russell, informing him that one could derive a contradiction in the system he had developed in the first volume.  Russell’s letter frames the paradox first in terms of the predicate P = ‘being a predicate which cannot be predicated of itself’, and then in terms of the class of all those classes that are not members of themselves.  Frege, in the Appendix to the second volume, rephrased the paradox in terms of his own system. 