Prohairesis (; variously translated as "moral character", "will", "volition", "choice", "intention", or "moral choice") is a fundamental concept in the Stoic philosophy of Epictetus. It represents the choice involved in giving or withholding assent to impressions. The use of this Greek word was first introduced into philosophy by Aristotle in the Nicomachean Ethics. To Epictetus, it is the faculty that distinguishes human beings from all other creatures. The concept of prohairesis plays a cardinal role in the Discourses and in the Manual: the terms "prohairesis", "prohairetic", and "aprohairetic" appear some 168 times.