The "Prolegomena to Pure Logic," which comprise[s] the introductory part of the Logical Investigations, seek[s] to blaze a new trail in the conception and treatment of logic. It attempt[s] to show that the exclusively psychological grounding of logic, to which our age ascribes so great a value, rests on a confusion of essentially distinct classes of problems, on presuppositions erroneous in principle concerning the character and the goals of the two sciences which are involved here — empirical psychology and pure logic. In detailed analyses, the epistemological and especially the sceptical complications which are necessarily indigenous to a psychologistic logic are revealed and, at the same time, it is also proved that the inadequate treatment of the hitherto existing logic, its lack of clarity and theoretical rigor are due to a misconception of the most essential foundations and problems. Directed against the dominant psychologism, the "Prolegomena" thus seek[s] to revive the idea of a pure logic but, in addition, also to give it a new shape. It result[s] in the demarcation of a theoretical science independent of all psychology and science, a science which embraces within its natural boundaries the entirety of pure arithmetic and theory of manifolds.