 No issue concerning Alcmaeon has been more controversial than his date. Some have sought to date him on the basis of his address to Brotinus (e.g., Zhmud 2012a, 122). Brotinus’ dates are too uncertain to be of much help, however. If he is Theano’s father and Theano was Pythagoras’ wife, he could be a contemporary of Pythagoras (570–490) or even older. If he is Theano’s husband and she was a student of Pythagoras in his old age and thus twenty in 490, Brotinus could have been born as late as 520. This suggests that Brotinus could have been the addressee of the book any time between 550 and 450 BCE. The center of controversy, however, has been a sentence in the passage of Aristotle’s Metaphysics discussed above: