 Galileo objects specifically to two principles of a contemporary version of the Aristotelian stance: that mathematics is only accidentally applicable to material things and the doctrine of proper and common sensibles. A proper sensible is an object that is directly perceived by only one sense—color, by sight alone; sound, by hearing, etc. The faculty and its proper object are said to be fitted to each other so that use of that faculty seldom results in misperception of the quality special to it. By contrast, the common sensibles—size. figure, motion/rest—are directly perceived by more than one sense; as a result, we are supposedly more liable to mistakes about them. Galileo’s objection reconceives the condition that makes perception of a body veridical or deceptive. (Crombie 1972: 74–9; Piccolino &amp; Wade 2008: 1312–15) He argues that the appearance of a body corresponds to the properties of the body that are its cause;. It is not up to . philosophy to say how various apearances are related to the affections of the objects we perceive; rather it requires the technical methods of natural philosophy. For example, to avoid being deceived by the broken visual appearance of an oar half in water, we need to find the physical cause of the appearance. This will show that the visual appearance is correct. According to Galileo’s epistemology, we should assume appearances do not exhibit the properties of their causes but rather something from which we may be able to figure them out.