Intimacy makes us happy because it helps us to feel truly justified. This was something I described in detail in my book The Happiness Paradox. To feel justified is to have that feeling of recognition, applause, acknowledgement, acceptance in a way that is consonant with who we are in all our strangeness. Intimacy provides a peculiarly intense form of justification.

Stendhal's observation that “Everything can be acquired in solitude, except character” reminds us that in order to feel justified in this way one cannot do it alone. It depends on validating recognition from another. But anyone else will not do. The other person needs to be a potent audience if the justification is going to be worth having. Adoring fans, uncritical adulation, blind loyalty all fall short. As for comedians standing in front of a live audience, the cheering only means something to us if it comes with the risk of jeering. Canned laughter is not enough. And because “intimacy” implies something secret and important revealed, it brings vulnerability through risk of exposure. An exposed cheek might be kissed, or slapped. I can picture a scene in the television programme The West Wing between Josh Lyman and his boss Leo McGarry, two of the Whitehouse senior staff, who have a very close and affectionate conversation, after which Leo appears to put his arms out as if to say “we're fine”.