To know a person’s nature is to know how they behave in different situations, in different roles, not how they behave in one isolated role. Even if we were to believe, as we surely must, that we put on a front in some situations more than others, there is no justification for privileging solitude as the state which reveals the truth as to how we are. For one thing, it is not obvious that we play no roles when alone. Indeed, in many cases, privacy allows us to indulge the most deluded fantasies about our identities. It can be easier to convince yourself you are a rock god playing guitar in your garage than it is in front of people whose faces reveal you are no such thing. […] Alone, the image we may hold of ourselves may be no true reflection, but a flattering portrait produced by the magic mirror of vanity.
– Julian Baggini, The Ego Trick (2011)