This work served as the main source of Czech historical and national consciousness until the end of the 18th century, when numerous errors and fabrications contained in it were recognized.
A scion of a noble family based in Libočany near Žatec, western Bohemia, Hajek was ordained priest of the Kostelec parish near Budyně nad Ohří in 1520.
Hajek initially was a member of the Bohemian Unity of the Brethren but later converted to Catholicism (a significantly minority religion in otherwise Protestant Bohemia at that time).
In 1524 he served as a preacher at the St. Thomas' Church in Prague quarter Malá Strana (Lesser Town); from 1527 as a dean of Karlštejn Castle and a priest in Tetín.
Hájek reached the peak of ecclesiastical career when he became provost of Stará Boleslav Chapter, however, he fell from grace shortly afterwards and retired to Prague.