Appearances to the mind are of four kinds. Things either are what they appear to be; or they neither are, nor appear to be; or they are, and do not appear to be; or they are not, and yet appear to be. Rightly to aim in all these cases is the wise man's task.
Epictetus (1866). “The Works of Epictetus: Consisting of His Discourses, in Four Books, the Enchiridion, and Fragments”, p.76
