>A friend of mine is doing his thesis about the history of the continuum
>and its models (from ancient times until the categorial models). Could
>you suggest me some texts (available books or articles) he could use?
For the beginnings, certainly Aristotle's *Physics* (Book V) is the
earliest text with any substance. There is a good collection of papers,
*Infinity and Continuity in Ancient and Medieval Thought*, edited by Norman
Kretzmann (Cornell University Press, 1982), which undoubtedly contains
references to a wider literature.
For the 19th C., Dedekind's *Stetigkeit und irrationale Zahlen* is a good
reference.
For contemporary, besides Machover's suggestions, there is the more
demanding collection of papers *Set Theory of the Continuum*, edited by H.
Judah, W. Just, and H. Woodin. Mathematical Sciences Research Institute
publication #26, Berlin: Springer-Verlag 1992.
Bill Tait