The Philosophy of the Upanishads c7.s2.2

c7.s2.2

It is easy to show how this thought, which met with adequate recognition first in the philosophy of Kant, but which existed in less clearly defined form from the earliest times, is the basis and tacit presumption, more or less consciously, of all philosophy, so far at least as this name is not made to serve as a mere cloak for empirical sciences. For all philosophy, as contrasted with empirical science, is not content to learn to know objects in their circumstances and surroundings, and to investigate their causal connections; but it rather seeks beyond all these to determine their nature, inasmuch as it regards the sum-total of empirical reality, with all the explanations offered by the empirical sciences, as something which needs to be yet further explained; and this solution is found in the principle which it sets forth, and from which it seeks to infer the real nature of things and their relation. This fact, then, that philosophy has from the earliest times sought to determine a first principle of the universe, proves that it started from a more or less clear consciousness that the entire empirical reality is not the true essence of things, that, in Kant’s words, it is only appearance and not the thing in itself.