" Seek at once, therefore, to be able to say to every unpleasing semblance, “You are but a semblance and by no means the real thing.” And then examine it by those rules which you have; and first and chiefly by this: whether it concerns the things which are within our own power or those which are not; and if it concerns anything beyond our power, be prepared to say that it is nothing to you. "

― Epictetus , The Art of Living: The Classical Manual on Virtue, Happiness and Effectiveness