“When You’re Smiling (The Whole World Smiles with You),” first published in 1928 by Shay, Fischer, and Goodwin, has been recorded by many artists. My favorite is the 1929 version by Louis Armstrong. “Oh, when you smilin’, when you smilin’, the whole world smiles with you. Yes, when you laughin’, when you laughin’, yes the sun come shinin’ through.” The song has a calm, lilting melody and a few basic observations that psychological science somewhat bears out.