It's the pastoral tradition, going back to Theocritus & Virgil & probably beyond, in which the Golden Age of Arcadian simplicity was always lamentingly contrasted with the modern times of corrupt sophistication.

'"O tempora o mores" is a sentence by Cicero in the fourth book of his second oration against Verres (chapter 25) and First Oration against Catiline. It translates as Oh the times! Oh the customs! (Oh what times! Oh what customs!) ...
In his opening speech against Catiline, Cicero deplores the viciousness and corruption of his age.' Wikipdedia

~M~