"It will be seen that difficulties for a 'checkmate' of the hostile Queen must chiefly arise from her great mobility which enables her to escape to safety with some degree of ease, in contrast with the King's poor slow power to move out of grave dangers. Victory in Co-regal will be in general achieved by checkmate of the enemy King. [...] A player must acquire two new habits at least. He must crush all his desires to make some brilliant Queen sacrifice. When he attacks the hostile co-regal Queen, he is obliged to give the polite word 'check' as warning!"