Lively interest was generated by Talbott’s book, FERMAT’S LAST THEOREM, since he provided substantial evidence that Fermat could indeed have had a good proof before he died in 1665. Readers have suggested that a more formal statement of the proof be given, and this suggestion has been followed in DERIVATIVES IN CARDINAL ARITHMETIC. Talbott’s book is sound, but this new paper makes the logic specially clear, and is a suitable conclusion to a long standing mathematical mystery.