 In his published writings, Dedekind does not provide an explicit answer to our first sub-question. What suggests itself from a contemporary point of view is that he relied on the assumption that the rational numbers can be dealt with in terms of the natural numbers together with some set-theoretic techniques. And in fact, in Dedekind’s Nachlass explicit sketches of two now familiar constructions can be found: that of the integers as (equivalence classes of) pairs of natural numbers; and that of the rational numbers as (equivalence classes of) pairs of integers (Sieg &amp; Schlimm 2005, earlier Dugac 1976). It seems that these constructions were familiar enough at the time for Dedekind not to feel the need to publish his sketches. (There is also a direct parallel to the construction of the complex numbers as pairs of real numbers, known to Dedekind from W.R. Hamilton’s works, and a more general connection to the use of residue classes in developing modular arithmetic. For the former cf. Ferreirós 1999, ch. 7, for the latter Dedekind 1857 and Dugac 1976.)