The use of 39- and 27-year generations for dynasties of kings was common in Greek chronography, and seems to have been extended to the ‘successions’ of literary figures by Apollodoros and his school. This was made possible by wide and liberal use of thirds of generations, i.e. intervals of 13 and 9 years, and a complete system was erected on the basis of the equation 39 × 3 = 27 × 4⅓. In its final form (shown in the table below) the system consisted of: (i) eight 39-year generations divided into thirds and dated 780–468, the fifth, sixth, and seventh generations being marked by Thales' birth, akme, and death respectively; (ii) one 27-year series crosses this 39-year line at 741, 624, and 507—Apollodoros calculates 27 × 16⅓ years along this line from Homer to the Persian Wars (912–480); (iii) the second 27-year series crosses the 39-year line at 702, 585, and 468—Apollodoros calculates 27 × 12⅔ years from Hesiod to the Peloponnesian War (774–432); (iv) the third 27-year series crosses the 39-year line at 780, 663, and 546—Apollodoros uses this series only for Anaximenes, and possibly Xenophanes.