 In 1895 and 1897, Cantor published his last two articles. They were a well-organized presentation of his results on the transfinite numbers (cardinals and ordinals) and their theory, and also on order types and well-ordered sets. However, these papers did not advance significant new ideas. Unfortunately, Cantor had doubts about a third part he had prepared, which would have discussed very important issues having to do with the problem of well-ordering and the paradoxes (see below). Surprisingly, Cantor also failed to include in the 1895/97 papers a theorem which he had published some years before which is known simply as Cantor’s Theorem: given any set \(S\), there exists another set whose cardinality is greater (this is the power set \(\mathcal{P}(S)\), as we now say—Cantor used instead the set of all functions of the form \(f\): \(S \rightarrow \{0, 1\}\), which is equivalent). In the same short paper (1892), Cantor presented his famous proof that \(\mathbf{R}\) is non-denumerable by the method of diagonalisation, a method which he then extended to prove Cantor’s Theorem. (A related form of argument had appeared earlier in the work of P. du Bois-Reymond [1875], see among others [Wang 1974, 570] and [Borel 1898], Note II.)