A Cross-National Study of Adolescent Self-Image Adolescence is not, as has been previously assumed, a developmental stage that was defined after the industrial revolution. There is substan- tial historical evidence to suggest that adolescence and youth, as a stage, was recognized by the ancient Romans, Greeks, and even Egyp- tians. The concept survived through the Dark Ages. In Le Grand Pro- prietaire, written in 1556, it is stated: "The third age,...