Stephen Cave at The Financial Times:
For most of the past 2,000 years of western culture, happiness on earth was considered neither achievable nor desirable. “Cursed is the ground for thy sake; in sorrow shalt thou eat of it all the days of thy life,” said God to Adam, in an early example of expectations management. But Christians also saw this misery as the key to the life-to-come: “Whosoever doth not bear his cross,” said Jesus, “cannot be my disciple.” And if the days before painkillers weren’t sorrowful enough already, the faithful would flail their backs to hasten their way to beatitude.
So how did happiness change from being a sin to our foremost earthly goal? The answer in short is that western culture retained the promise of paradise but brought it forward from the next world into this one. The process took a few hundred years, beginning with the Renaissance and the Reformation. But it owes most to the thinkers of the Enlightenment, who combined the Christian belief in progress towards a happier state with a new faith in science and reason. In doing so, they wrote the script to which we still speak: a doctrine that says we can have heaven here and now if only we try hard enough.