What could Arthur Schopenhauer, the German pessimist and speculative metaphysician of the irrational will, possibly have in common with Thomas Reid, the staid and pious apostle of common sense? Unlike their contemporaries, both philosophers distinguished carefully between sensation and perception. In this essay I examine their respective formulations of the sensation / perception distinction, and I attempt to explain where they agree and where they diverge. Such an examination seems long overdue, for no-one – to the best of my knowledge (...) – has bothered to compare their views on this subject. (shrink)