"If we have no aptitude or natural taste for geometry this does not mean that our faculty for attention will not be developed by wrestling with a problem or studying a theorem. On the contrary it is almost an advantage. ... Without our knowing or feeling it, this apparently barren effort has brought more light into the soul. ... Every time that a human being succeeds in making an effort of attention with the sole idea of increasing his grasp of truth, he acquires a greater aptitude for grasping it, even if his effort produces no visible fruit."