 The mistake of supposing tastes, etc. are qualities that inhere in inanimate bodies is charged not to our senses, but to the use of language. It seems we give names to the primary affections which we know to exist in bodies and we give names to the sensations of our SQs as well. This makes us believe the names of the latter apply to bodies just as the names of the former do. According to Galileo, the names of SQs signify nothing when used in this way. This poses a challenge to the traditional Aristotelian scholastic theory of sense perception. According to Aristotle, the nature of sentient beings assures that they acquire perceptual knowledge in an environment such as ours. Some care is called for, but no special effort is generally needed. On Galileo’s theory, many sense perceptions are caused by insensible particles whose properties are by no means easy to know. When a fire makes us warm, it is easy to feel the warmth but the rapid motion of particles that causes it has to be discovered by rigorous-s use of an effective method of natural philosophical inquiry.