Throughout history, wearing facial hair or choosing to be clean-shaven has often become symbolic of a generational difference. In the ancient world, older men equated beards with sagacity, but as the fashion for shaving grew more widespread, younger men began to ridicule the sight of a man with a full beard. In the first century AD, Lucian of Samosata, a Greek satirist and writer, famously commented, ‘If you think that to grow a beard is to acquire wisdom, a goat with a fine beard is at once a complete Plato.’
Source: Moustaches, Whiskers & Beards, Lucinda Hawksley