My point of view is, brieﬂy, that our ordinary language is full of theories: that observation is always observation in the light of theories; that it is only the inductivist prejudice which leads people to think that there could be a phenomenal language, free of theories, and distinguishable from a 'theoretical language'; and lastly, that the theorist is interested in explanation as such, that is to say, in testable explanatory theories: applications and predictions interest him only for theoretical reasons because they may be used as tests of theories.