During the 1660s and 1670s, Thomas Willis (1621–1675) pursued an ambitious program of brain science. Instead of the speculative approach favored by René Descartes (1596–1659), Willis used comparative anatomy to figure out the workings of the brain and nerves. As a result, Willis is still cited by science writers as the “founder” of the modern neurosciences.

This chapter, by contrast, builds on a wealth of scholarship showing that Willis in fact had aims that few scientists would recognize. One of his key objectives, for instance, was to work out how much influence the immaterial, immortal soul had over the mechanisms of the human body. Despite his empiricism, moreover, Willis relied to a large extent on the imagination in his efforts to hypothesize mechanisms for complex cognitive and neurological processes.

For the most part, scholars have argued that Willis used such strategies because of an unfortunate tendency to frame hypotheses even when the evidence was lacking. In this chapter, however, I show that the imagination played a surprisingly important role in the neurosciences of the seventeenth and eighteenth centuries, thereby challenging modern assumptions about the shape and causes of progress in brain research.