Page:Clavis universalis (IA clavisuniversali00colliala).pdf/26

of the case as we know them point to the independence of Collier's thought. In point of time, the promulgation of these doctrines is almost identical. In 1709, George Berkeley published his "Essay toward a New Theory of Vision," which contained suggestions of his metaphysical theory. For the purpose of his arguments he grants, in this work, the external existence of tangible matter, but he teaches, by implication, that visible matter exists only in the mind of him who sees it. In 1710, Berkeley published the "Principles of Human Knowledge," which contains the exposition of his doctrine in detailed form. This was followed, in 1713, by the "Three Dialogues between Hylas and Philonous," intended, as Berkeley says, "to introduce the notions I advance into the mind in the most easy and familiar manner." In this same year, 1713, appeared Collier's little volume, the "Clavis Universalis." The facts that Berkeley's first suggestion of his theory was published four years before Collier's theory was advanced, and that his finished arguments were made public three years before Collier's, seem at first glance to settle in the negative the question of Collier's independence. But two further considerations make the conclusion doubtful. In the first place, we know by Collier's own word^[1] that he had adopted his own theory ten years before he put it into outward form, which brings the date of its conception not