The central unifying element in the philosophy of Peter Browne (d. 1735) is his theory of analogy. Although Browne's theory was originally developed to deal with some problems about religious language, Browne regards analogy as a general purpose cognitive mechanism whereby we substitute an idea we have to stand for an object of which we, strictly speaking, have no idea. According to Browne, all of our ideas are ideas of sense, and ideas of sense are ideas of material things. Hence we can conceive of spiritual things – including even our own spirit – only by analogy. One interesting application Browne makes of his theory is an account of how concepts such as knowledge can be correctly applied to beings that have no intrinsic properties in common, such as non-human animals, humans, angels, and God. I argue that this is best understood as what, in the contemporary literature, is known as a 'multiple realizability' problem and that Browne's solution to this problem has important similarities to functionalist theories in recent philosophy of mind.