Objectively and apart from our cognition, aspects of truth may, for aught we know, be diverse and multiform; in the infinity of space and time we have no adequate reason for affirming that they are not; but we cannot without the most gratuitous mental suicide allow the subjective co-existence of antagonistic convictions both claiming to be true at the same time. We must maintain, I think, the indivisibility of consciousness not only as an ultimate postulate of truth, but as a sine qua non of all affirmation and ratiocination of whatever kind. I am aware that this position — the ultimate veracity of consciousness, has been questioned; indeed, in a dialectical mood I have frequently questioned it myself, and in my own opinion not unsuccessfully so far as formal ratiocination is concerned. For that matter, I have had too long an experience of the subtleties and multiform aspects of logic not to know that there is no principle which can be formulated as an axiom of truth which unscrupulous dialectic cannot undermine. Even the ‘Cogito, ergo sum,’ of Descartes may be shown to be open to innumerable objections both as to form and substance. But while I think those extreme exercitations not only harmless in themselves but useful as intellectual gymnastics — just as the paradoxes of the higher mathematics may be useful — I nevertheless regard them as mere brutem fulmen when employed seriously to destroy consciousness: at most they can only result in setting reason to destroy reason — a mere self-stultifying and utterly ineffective operation. Reason and the direct deliverances of consciousness have a vitality much too inherent to succumb to attacks of formal logic, no matter how adroitly planned or how skilfully conducted. The dialectician who in earnest undertakes such a task is engaged in an enterprise much more fruitless than the ancient battle with the Hydra: the heads he amputates replace themselves with greater facility — the life he supposes himself to take is but the precursor of renewed vitality. From this standpoint of reason and consciousness we must, then, pronounce against all extreme forms of double-truth.