Privacy is a protection from the unreasonable use of state and corporate power. But that is, in a sense, a secondary thing. In the first instance, privacy is the statement in words of a simple understanding, which belongs to the instinctive world rather than the formal one, that some things are the province of those who experience them and not naturally open to the scrutiny of others: courtship and love, with their emotional nakedness; the simple moments of family life; the appalling rawness of grief. That the state and other systems are precluded from snooping on these things is important - it is a strong barrier between the formal world and the hearth, extended or not - but at root privacy is a simple understanding: not everything belongs to everyone.