I checked the TAC reprint of Beck's *Triples, Algebras, and Cohomology* from 1967. It is evident from the discussion at pag. 8, before Thm. 1 that tripleability was not presented by Beck before his thesis (1967). There, Beck promises a paper "to appear", whose intended title was *The tripleableness theorems*. The TAC reprint has an editor's note in the bibliography commenting on this paper.

> Editors’ note: To our knowledge, this has not appeared. Beck’s tripleableness theorems have been exposed in M. Barr and C. Wells, Toposes, Triples and Theories. Springer-Verlag, Berlin, Heidelberg, New York, 1984 as well as other places.

My impression is thus that Beck was writing the paper while working on his thesis in 1966. When people refer to this *forgotten manuscript* they are actually referring to the discussion before Thm 1, a draft that maybe has circulated in a very sketchy form among very selected people and was probably never finished.

I also checked the papers that cite this *The tripleableness theorems* and judging from the 3 citations of Paré, he might have seen the manuscript. Barr cites it once too.