 This is usually discussed in connection with qualities of the sort Boyle calls “sensible”. These are our SQs—in fact, on two occasions, Boyle refers to them as “secondary qualities”. Sensible qualities are present in bodies that operate on human beings so as to cause the sort of ideas on account of which we ascribe colors, etc. to bodies. Names given to the various ideas of SQs are also used to designate the corresponding qualities, so “color”, “green”, etc. can be used to stand for qualities in the scope of corpuscularian explanation (OFQ [1991: 24, 30–4, 51–2]). Boyle is a Cartesian mind-body dualist. Although he discusses perception in several texts, he has no well developed account (see Anstey 2000: 68–85). OFQ sticks to the physical project announced at the start.