Friedrich Aldolf Trendelenburg (1802–1872), an often neglected yet fundamental thinker for understanding the evolution of philosophy in Germany following the great idealist systems, notes that, with Herbart, one has the impression of breathing "another air." Compared to the speculative arbitrariness of the "poetic philosophers' (HSW 8:73), Herbart is more attentive to the data of experience, data that metaphysics should not "reconstruct" on the basis ofa prioriprinciples, but simply "liberate" from internal contradictions.