In an unpublished manuscript titled , Germain showed that any counterexamples to Fermat's theorem for "p" > 5 must be numbers "whose size frightens the imagination", around 40 digits long. Germain did not publish this work. Her brilliant theorem is known only because of the footnote in Legendre's treatise on number theory, where he used it to prove Fermat's Last Theorem for "p" = 5 (see Correspondence with Legendre). Germain also proved or nearly proved several results that were attributed to Lagrange or were rediscovered years later. Del Centina states that "after almost two hundred years her ideas were still central", but ultimately her method did not work.