 The virtues, like everything else in one’s will, are a response to reasons. But practical reasons (i.e. reasons for action) are propositional: they can be stated as principles and other standards, more or less specific. So principles, ultimately the first principles of practical reason (that is, of natural law), are more fundamental to ethics than virtues are. Aquinas accepts Aristotle’s notion that every virtue is a mean between too much and too little, and he constantly stresses that it is reason – with the principles and rules (regulae) it understands – that settles the mean and thus determines what is too much or too little. Indeed, the principles of practical reason (natural law) establish the ends of the virtues: ST II-II q. 47 a. 6. And the master virtue of bringing practical reasonableness into all one’s deliberations, choices, and carrying out of choices – the virtue of prudentia, a virtue both intellectual (of one’s intelligence) and moral (of one’s whole will and character) – is part of the definition, content, and influence of every other moral virtue: ST I-II q. 65 a. 1, q. 66 a. 3 ad 3, etc.