[2] The English translator of the same book reveals (in footnote 3) one other aspect in Oenopides life which was his travel in Egypt in which he enriched his knowledge in the art of Astronomy and Geometry by some Egyptian priests.
[2] The main accomplishment of Oenopides as an astronomer was his determination of the angle between the plane of the celestial equator, and the zodiac (the yearly path of the Sun in the sky).
In actual practice this is only approximately true, because the ratio of the length of the year and that of the month does not exactly match any simple mathematical fraction, and because in addition the lunar orbit varies continuously.
However, a 59-year period had the advantage that it corresponded quite closely to an integer number of orbital revolutions of several planets around the Sun, which meant that their relative positions also repeated each Great Year cycle.
While Oenopides's innovations as an astronomer mainly concern practical issues, as a geometer he seems to have been rather a theorist and methodologist, who set himself the task to make geometry comply with higher standards of theoretical purity.