  The supremacy of conscience in human nature can also be shown by a comparison of the constitutions and natures of animals with human nature. Animals are driven by principles similar to (or identical to) those that give rise to human actions: they share many of our passions and they too are driven by self-interest. When animals act according to these principles they act appropriately to their natures (in senses N1 and N2). But humans have a principle, conscience, which animals lack. This suggests that humans do not act suitably to what is distinctive to their whole nature, and in particular suitable to that end which draws on many of the principles of human nature when they act only from those principles that they share with animals and not according to conscience.