  With this as his methodological foundation, he places Locke, Condillac, Reid and Dugald Stewart among those whose explanation of the fact of thought is deficient; Plato, Aristotle, Leibniz and Kant are listed amongst those whose explanation is in many ways excessive. In other words, he distinguishes between sensationalists who, according to him, cannot explain the origin of ideas, and idealists who posit in their explanation more ideas or forms than are necessary. For him, however, human thought must depend upon the innate idea of being, without which nothing is intelligible. We cannot think of what is not. At the same time, nothing more is needed than the single idea of being, and its possible determinations, brought about through sensation, to explain all intellectual principles and the ramifications of thought.