Epiphanius, in his De Mensuris, gives an account of these two men. The former published his version of the Old Testament in the year 181. The latter put forth his translation half a century earlier, about 129 a.d. This reference to the version of Theodotion furnishes a note of date as to the time when Irenæus published his work: it must have been subsequently to a.d. 181.