 The theory of natural law gives us Aquinas’s moral theory: it identifies the foundations of ethics and frames the general contours of the moral law. For us to adhere to that law, however, it is not enough to trust to the light of intellect and our natural inclinations. Reliably moral agents must, in addition, cultivate the right sorts of virtuous dispositions. Accordingly, Aquinas develops a complex  virtue ethics  to frame his account of our moral psychology.