Edmund Husserl Ideas, Volume One.(1913) Translated into English.
This work is the true foundation of phenomenology as the transcendental science of pure consciousness; it becomes the foundational science of all sciences, allegedly replacing all metaphysics, or "first philosophy". Husserl struggled with and profoundly explored the Cartesian postulate of the ego, single-mindedly probing its enigmatic conundrums in an effort to give a perfectly lucid and precise account of what philosophic man is.