Unreflexive common sense thinks of sense-perception as a direct grasping of the nature of the physical world. But when we are confronted with facts about sensory illusion, about the physical and physiological causes of perception, and with modern scientific views of the real nature of matter, it is hard to maintain such a “Direct Realist” theory of perception. We tend to substitute a Copy or Representative theory which puts sense-impressions between ourselves and physical reality. Some philosophers overwhelmed by the difficulties of the Copy theory, retreat into Phenomenalism, which identifies the physical world with our sense-impressions. – The author contends that there are insuperable difficulties for the Representative and Phenomenalist theories. He re-examines all the traditional objections to a Direct Realist theory, and tries to show that they can be overcome. – Part One, «Are the sensible qualities subjective ?» : 1, Arguments to prove the sensible qualities subjective (from sensation, from the relativity of sensible qualities, from illusion); – Part Two, «The argument from illusion» : 2, What are the immediate objects of awareness in perception ?; 3, Refutation of the representative theory of perception (We have no reason to believe in the existence of the physical objects postulated by the representative theory; On the representative theory, there can be no resemblance between sense-impressions and physical objects; The conception of a physical object which cannot be immediately perceived is illogical); 4, Some features of sense-impressions (Can there be sense-impressions nobody has ?; Are sense-impressions just as they appear to be ?); 5, Refutation of phenomenalism, 1 (The phenomenalist gives unperceived physical objects a merely hypothetical existence; The phenomenalist must admit that a universe that contains no minds contains no matter either; Physical objects, which are determinate, cannot be constructions out of indeterminate sense-impressions); 6, Refutation of phenomenalism, 2 (Difficulties for the phenomenalist account of space and time; Phenomenalism can give no account of the numerical difference of minds that exist at the same time; Phenomenalism can give no satisfactory account of the nature of a mind); 7, An analysis of sensory illusion (Sensory illusion as false belief that we are perceiving; “Perception without belief”; Is “perception without belief” essentially belief-inducing ?; A psychological explanation of the occurrence of some sensory illusions); – Part Three, «The argument from verification» : 8, The argument from verification; 9, The nature of perception (Perception always involves the acquiring of knowledge of particular facts about the physical world, by means of our senses; Perception is nothing but the acquiring of knowledge of particular facts about the physical world, by means of our senses); 10, Consequences of our account of the nature of perception (The existence of unconscious perception; Are there intermediate cases between veridical and illusory perception ?; Reformulation of the empiricist theory of the way we acquire empirical concepts; The distinction between sensory illusion and hallucination; The nature of sense-impressions; The argument from verification answered); – Part Four, «The argument from causation» : 11, The argument from causation (The argument from the time-gap); – Part Five, «The argument from science» : 12, The argument from science (Scientific phenomenalism; Difficulties for scientific penomenalism); 13, Direct realism without scientific penomenalism (Can scientific findings undermine perception ?; The argument from paradigm cases); 14, Problems about the secondary qualities (The apparent simplicity of the secondary qualities; Are the secondary qualities really simple ?; Can the secondary qualities be reduced to primary qualities ?); 15, Can physical objects have nothing but the primary qualities ? – Conclusion. M.-M. V.