 After his Habilitation, Brentano had started to work on a large scale work on the foundations of psychology, which he entitled Psychology from an Empirical Standpoint. The first volume was published in 1874, a second volume (The Classification of Mental Phenomena) followed in 1911, and fragments of the third volume (Sensory and Noetic Consciousness) were published posthumously by Oskar Kraus in 1928.