Further, there is no trustworthy standard by which we can separate the “real” from the “unreal” aspects of phenomena. Such standards as exist are conventional: and correspond to convenience, not to truth. It is no argument to say that most men see the world in much the same way, and that this “way” is the true standard of reality: though for practical purposes we have agreed that sanity consists in sharing the hallucinations of our neighbours. Those who are honest with themselves know that this “sharing” is at best incomplete. By the voluntary adoption of a new conception of the universe, the fitting of a new alphabet to the old Morse code — a proceeding which we call the acquirement of knowledge — we can and do change to a marked extent our way of seeing things: building up new worlds from old sense impressions, and transmuting objects more easily and thoroughly than any magician. “Eyes and ears,” said Heracleitus, “are bad witnesses to those who have barbarian souls”: and even those whose souls are civilized tend to see and hear all things through a temperament. In one and the same sky the poet may discover the habitation of angels, whilst the sailor sees only a promise of dirty weather ahead. Hence, artist and surgeon, Christian and rationalist, pessimist and optimist, do actually and truly live in different and mutually exclusive worlds, not only of thought but also of perception. Only the happy circumstance that our ordinary speech is conventional, not realistic, permits us to conceal from one another the unique and lonely world in which each lives. Now and then an artist is born, terribly articulate, foolishly truthful, who insists on “Speaking as he saw.” Then other men, lapped warmly in their artificial universe, agree that he is mad: or, at the very best, an “extraordinarily imaginative fellow.”
Moreover, even this unique world of the individual is not permanent. Each of us, as we grow and change, works incessantly and involuntarily at the re-making of our sensual universe. We behold at any specific moment not “that which is,” but “that which we are”, and personality undergoes many readjustments in the course of its passage from birth through maturity to death. The mind which seeks the Real, then, in this shifting and subjective “natural” world is of necessity thrown back on itself: on images and concepts which owe more to the “seer” than to the “seen.” But Reality must be real for all, once they have found it: must exist “in itself” upon a plane of being unconditioned by the perceiving mind. Only thus can it satisfy that mind’s most vital instinct, most sacred passion — its “instinct for the Absolute,” its passion for truth.