[1] The phrase epitomizes the renewed study of Greek and Latin classics in Renaissance humanism,[2] subsequently extended to Biblical texts.
)The phrase in the humanist sense is associated with the poet Petrarch, whose poems Rerum Vulgarium Fragmenta (c.1350) use the deer imagery of the Psalm.
[1] Erasmus of Rotterdam used the phrase in his De ratione studii ac legendi interpretandique auctores:[5] Sed in primis ad fontes ipsos properandum, id est graecos et antiquos.
)For Erasmus, ad fontes meant that to understand Christ in the Gospels in an educated way involved reading good translations of the New Testament, and the Greek and Roman philosophers and Church Fathers in the five hundred years surrounding Christ, over the earlier Old Testament and later Scholastics.
[5] The most extreme version of ad fontes was the Protestant Reformation called for renewed attention to the Bible as the primary source of Christian faith, to the extent of denying extra-biblical apostolic teaching authority: sola scriptura.