  Although cognitive mechanisms provide the main focus, a variety of other animal functions, including nutrition and locomotion, are covered by this part of the book. Among the gems is a digression attacking the teleologists’ mode of physiological explanation (4.823–57). To explain bodily limbs and organs on the model of artefacts, as divinely created for the sake of their use, is a misapplication of the craft-nature analogy. Artefacts were invented for the better fulfilment of functions that already existed in nature—cups to facilitate drinking, beds to improve sleep, weapons for more effective fighting. No analogous story can be told about e.g., the eye being created for seeing, because before there were eyes there was no such function as seeing.