  His discussion of tertiary qualities is similar. If we knew the “Figure, Size, Texture, and Motion of the minute Constituent parts of any two Bodies”, we would then be able to derive tertiary qualities; we would be able to deduce that opium causes sleep, and we would understand why (E IV.iii.25, pp. 555–56; see also E IV.iii.13, p. 545). In all of these passages, then, and in many similar ones, Locke at least appears to accept at least some components of the corpuscular hypothesis—that material bodies are compounded from minute particles, and that certain observable qualities are reducible to the particles’ primary qualities of size, shape, and motion. This tendency to speak as though the corpuscular hypothesis is true, either in whole or in part, has been termed Locke’s “dogmatic” side (Downing 2007).