Every religion, ideology and creed has its shadow, and no matter which creed you follow you should acknowledge your shadow and avoid the naïve reassurance that ‘it cannot happen to us’. Secular science has at least one big advantage over most traditional religions, namely that it is not terrified of its shadow, and it is in principle willing to admit its mistakes and blind spots. If you believe in an absolute truth revealed by a transcendent power, you cannot allow yourself to admit any error – for that would nullify your whole story. But if you believe in a quest for truth by fallible humans, admitting blunders is an inherent part of the game.