The Newton of biology, he found the science of life a chaotic maze; he left it an orderly system, with a definite plan and a recognisable meaning. Great men are not accidents; great works are not accomplished in a single day. Both are the product of adequate causes. The great man springs from an ancestry competent to produce him; he is the final flower and ultimate outcome of converging hereditary forces, that culminate at last in the full production of his splendid and exceptional personality.