Phenomenology of Spirit
The Emperor's New Philosophy
While the charge by devoted Hegelians will be leveled at me that I clearly "misunderstood" Hegel, I will still maintain (with Schopenhauer, Kierkegaard & Jung) that it's just sophism. Leaving aside his highly unappealing and purposely abstruse
style, his entire theory of the Universal Consciousness is unprovable and, as such, pretty useless.
Just because it's confusing, doesn't mean it's profound.
However, it is de rigeur reading for anyone interested in subsequent philosophers since - love 'im or hate 'im, he was a seminal figure in the field of philosophy.