Are experience and stimulus necessarily alike? Wertheimer spoke of this as an “insidious and insistent belief”. By contrast, Watson devotes an entire book to the defense of the thesis that representation necessarily requires resemblance. I argue that this bold and important thesis is ambiguous between a historical and a systematic reading, and that in either one of these readings the thesis, for different reasons, will be found wanting. Second, a proper evaluation of it in either one of its possible interpretations (...) requires a careful analysis of the notion of resemblance. I proceed to supply some necessary distinctions and argue that, given such an analysis, Watson's thesis may be historically applicable only to ancient and medieval philosophy, while its systematic import is untenable. (shrink)