David Hume,
Philosophical Works, v. 2 (of 4…
“ A good-natured man finds himself in an instant of the same humour with his company; and even the proudest and most surly take a tincture from their countrymen and acquaintance. A cheerful countenance infuses a sensible complacency and serenity into my mind; as an angry or sorrowful one throws a sudden damp upon me. Hatred, resentment, esteem, love, courage, mirth and melancholy; all these passions I feel more from communication, than from my own natural temper and disposition. So remarkable a phenomenon merits our attention, and must be traced up to its first principles. ”
