" A fight is about more than just technique and skill,’ said Yael. ‘It is about heart and courage. About a willingness to suffer pain, a realisation that even the greatest warrior can still be humbled by a twist of fate, a patch of loose ground, a mote of dust in the eye...’

‘I account for random factors in my calculations,’ said Dahan, still unwilling to concede that his combat subroutines could be in error. ‘My results are certain.’

‘Therein lies your error,’ said Kul Gilad. ‘There is no such thing as certainty in a fight. Even our greatest bladesman could be felled by a lesser opponent. To be a truly sublime warrior, a man must realise that defeat is always possible. Only when you recognise that can you truly fight with heart. "

― Graham McNeill , Forges of Mars Omnibus