For George Berkeley, who speaks through the character of Philonous in the text, perception is existence. Berkeley’s motto, esse est percipi (to be is to be perceived) speaks directly to this argument. The argument is grounded in empiricism—a philosophical tradition holding that all we can know of the world is that which can be attained through direct experience. In the preface, Berkeley lays the groundwork for his argument, beginning by addressing the opposing view. He says, “Upon the common principles of philosophers, we are not assured of the existence of things from their being perceived. And we are taught to distinguish their real nature from that which falls under our senses. Hence arise scepticism and paradoxes” (3). Berkeley suggests in these remarks that rationalism, which enlists the use of reason and logic to gain knowledge of the world, creates skepticism. Continuing to diagnose the confusions that arise from rationalism, he adds sarcastically, “It is not enough, that we see and feel, that we taste and smell a thing. Its true nature, its absolute external entity, is still concealed. For, though it be the fiction of our own brain, we have made it inaccessible to all our faculties.