This work is a study of an important and difficult question in the theory of perception: how is the sensory content of Perception to be understood with-out conflicting with basic Convictions in ontology, epistemology, and the theory of science? The modern history of the philosophical theory of Perception in a sense is a history of unsuccessful attempts to find a place for the sensory content of perception in a coherent conception of the world and of our knowledge of the world. The present work considers the entire history of this Problem. The author discusses not only the relevant historical texts of Locke, Berkeley, Hume, Mill, and Russell but also the recent literature on perception. He discusses in detail the different variants of the sense-datum theory, the theory of representation and the different forms of phenomenalism, and convincingly points out their internal incoherence. The author criticizes Amstrong's and Pitcher's attempt to cope with the Problem of the sensory content of perception by reducing this content to the different modalities of belief. Schantz himself defends a version of the adverbial theory of Perception holding that, in dealing with the sensory content of perception we are involved with states of persons, which we best express by adverbial constructions. This Position, inspired by Chisholm and Sellars, is set forth in a more detailed way than is ususal in the existing literature. The author is able to show, finally, that the adverbial theory is compatible with a form of scientific realism; this leads to a new and original defense of the traditional distinction between primary and secondary qualities. Of interest to: Philosophers, logicians, linguists, psychologists