The Christians who engaged in infamous persecutions and shameful inquisitions were not evil men but misguided men. The churchmen who felt they had an edict from God to withstand the progress of science, whether in the form of a Copernican revolution or a Darwinian theory of natural selection, were not mischievous men but misinformed men. And so Christ's words from the cross are written in sharp-edged terms across some of the most inexpressible tragedies of history: 'They know not what they do'.