  Moral first principles, like other first principles God has placed in our natures, require experience in order to appreciate. In this very narrow way Reid compares moral first principles to mathematical axioms since those axioms are “not discerned till men come to a certain degree of maturity of understanding. ... In like manner, our Moral Judgment or Conscience, grows to maturity from an imperceptible seed, planted by our Creator” (EAP 5.1, 276–7). So, though moral principles are self-evident, they are only known to be true by those who have reached an age of maturity. This resonates with the lessons Reid derives from the requirements upon witnesses and judges in Scots law.