Mathematical rationality can be presented in a rosy picture if we pay particular attention to the way mathematics facilitated the Scientific Revolution and helped provide an insight into nature. More rosy colours can be added when the mathematical resources for technological development are portrayed. And finally a grandiose picture of mathematics as the sovereign of science may emerge when we pay attention to the intrinsic qualities of mathematics. This celebration represents the modern conception of mathematics including an unquestioned trust in its rationality. The assumption of a close correlation between scientific development and progress in general is part of the modern outlook. We should not forget, however, that this outlook developed in connection with the so-called great discoveries which also included some of humankind's most brutal colonisations.