Hegelian absolute idealism, far from implying an annihilating negation of the finite, means the capacity of the Idea of vivifying and being in itself in everything that exists - even in the non-important and most despicable forms. We will construct the authentic Hegelian idealism trough his Lectures on Plato, where Hegel already rejects the schlechten Idealismus on unilateralism grounds and finds a trought that embraces both reality and thinking. Therefore, the Idea cannot be a Chimera or remain locked in the Mind of God but must be immanent to the human and the natural. We will show how Hegel wavers (with his affirmations of the ideality of finite and the impotence of nature) and the limits of Platonism (the resistance to lose himself in the nonsense without ground to which hair, mud and garbage would lead), but also the conceptual necessity of an Idea that should leave no aspect of reality in the shadows. Doing so would mean disregarding the syllogism of syllogisms and enter in a nihilistic spiral of the history of an error.