Why are people unhappy? Think back to just about any historical period you like, from the remote past to times within living memory; imagine people then looking at us now and saying, "How dare you be unhappy? You haven't earned the right!"

It's hard to deny they'd have a point. We have peace, a high standard of living, relatively good health, long life, inexhaustibly abundant and endlessly varied entertainment, and of course mass technological empowerment that would have left any strutting god-king of old utterly aghast at what the meanest of us can do at the twitch of a thumb (which soon won't be necessary as the power of brainwaves are harnessed).

How would we justify our unhappiness — for unhappiness abounds — to past generations who had far better cause than we to know life's misanthropy and yet carried on regardless, grateful for what crumbs of joy they could wrest from their sullen, angry gods?