Erwin Straus nourished his spirit on "Act psychology", "Gestalt psychology" and "Husserlian phenomenology" in Berlin and Göttingen, and has renewed his engagement with these problems in Lexington without renouncing his commitment to a tradition to which he has remained always faithful. It is in the realm of the psychology of perception that Erwin Straus - as did the analyses of Bergson, Gestalt psychology, and the phenomenology of Husserl - made his point of departure for his critique of sensationistic empiricism and of the sensory psychophysiology from Johannes Miller to Wundt... The guiding idea of Erwin Straus, as Merleau-Ponty has so profoundly made explicit, is that the sphere of sensing, the sense of the senses, is discovered to be the constitution of the very corporeity of experience, the latter being capable of being lived only in and by a living body. As abstract an sophisticated as this primordial description of the phisical body might be insofar as it is the object and subject of phenomenology, it appears to me to be the only possible, or more simply, the only one which allows us to formulate a general law of the temporal organization (the arrow of time) of the existent, that is to say, of the human being in the proper constitution of his own becoming. The phenomenology that I have just outlined founds the system of reality as the very form of conscious being, and the organization of the psychical body as the constitution of the ego. Four theses within this framework relating perceptual and hallucinatory activity are (1): hallucination is virtual in perception, and that it is, as Ernest Hartman recently stated, an "ubiquitous capacity" immanent to this "psychical apparatus" of which Freud spoke, and which I prefer to call "the psychical body". (2) That hallucinatory difficulties are real difficulties and not a simple difference of intensity between the image and sensation. (3) The pathogenesis of hallucinations can only be theorized according to the (Hughlings) Jacksonian model of negative (a process of disorganization) and positive (the contents of the hallucinatory phenomenon); and (4) There is a fundamental distinction between the diverse forms and levels of delirious or psychotic hallucinatory activity and hallucinatory images.