It is a happy circumstance that this important aspect of method should be brought to our attention by a distinguished scientist in the field of biology. In the past any reference to the “psychical” by the scientific methodologist has been regarded as a dubious departure from his strict routine. But the recognition, finally, by a man of science, of the aleatory, autonomous character of a spontaneous universe, disclosed in biological directives as well as in the dynamics of the atom, is a stimulating enhancement of that philosophy which, as Dewey says, is “the critical theory of methods of criticism.”