Let us imagine Berkeley addressing himself to that infant or animal consciousness which first used the category of substance and passed from its perceptions to the notion of an independent thing. “Beware, my child,” he would have said, “you are taking a dangerous step, one which may hereafter produce a multitude of mathematical atheists, not to speak of cloisterfuls of scholastic triflers. Your ideas can exist only in your mind; if you suffer yourself to imagine them materialised in mid-air and subsisting when you do not perceive them, you will commit a great impiety. If you unthinkingly believe that when you shut your eyes the world continues to exist until you open them again, you will inevitably be hurried into an infinity of metaphysical quibbles about the discrete and the continuous, and you will be so bewildered and deafened by perpetual controversies that the clear light of the gospel will be extinguished in your soul.” “But,” that tender Peripatetic might answer, “I cannot forget the things about me when I shut my eyes: I know and almost feel their persistent presence, and I always find them again, upon trial, just as they were before, or just in that condition to which the operation of natural causes would have brought them in my absence. If I believe they remain and suffer steady and imperceptible transformation, I know what to expect, and the event does not deceive me; but if I had to resolve upon action before knowing whether the conditions for action were to exist or no, I should never understand what sort of a world I lived in.” “Ah, my child,” the good Bishop would reply, “you misunderstand me. You may indeed, nay, you must, live and think _as if_ everything remained independently real. That is part of your education for heaven, which God in his goodness provides for you in this life. He will send into your soul at every moment the impressions needed to verify your necessary hypotheses and support your humble and prudent expectations. Only you must not attribute that constancy to the things themselves which is due to steadfastness in the designs of Providence. _Think and act_ as if a material world existed, but do not for a moment _believe_ it to exist.” [Sidenote: Vain “realities” and trustworthy “fictions.”]