To understand the Scholastic treatment of taxes one must bear in mind that taxation, as we now know it—namely, as a routine, normal, and respectable method of providing for the financial needs of government—is a comparatively modern phenomenon. In feudal times, on the other hand, rulers derived their revenues mainly from personal estates, customary tributes and dues paid by their vassals, tolls on strangers and on traffic on roads and rivers, war booty, rapine and piracy, and, in times of special need, from ‘‘aids,’” subventions, donations, etc., ... All of St. Thomas’ references to taxation that I know of treat it as a more or less extraordinary act of a ruler which is as likely as not to be morally illicit.