 Such variation should not be surprising, for the natural law tradition was long and robust. Though there were ties to the ancient world, it began in earnest with Aquinas, since he was the first to formulate a group of ideas systematic enough to be called a theory. The tradition continued through the middle ages and into the early modern era before (allegedly) meeting its demise in Kant. Given that natural law was the dominant paradigm in ethics, politics and law for hundreds of years—much longer than the period from Kant to us—it is entirely predictable that theorists would have pushed that paradigm in so many directions. It may be that there is some essence shared by all natural law theories; for example, one recent commentator has suggested that the