Arthur Schopenhauer said this quote
“ In conformity with this spirit and aim of the Stoa, Epictetus begins with it and constantly returns to it as the kernel of his philosophy, that we should bear in mind and distinguish what depends on us and what does not, and thus should not count on the latter at all. In this way we shall certainly remain free from all pain, suffering, and anxiety. Now what depends on us is the will alone, and here there gradually takes place a transition to a doctrine of virtue, since it is noticed that, as the external world that is independent of us determines good and bad fortune, so inner satisfaction or dissatisfaction with ourselves proceeds from the will. But later it was asked whether we should attribute the names *bonum et malum* to the two former or to the two latter. This was really arbitrary and a matter of choice, and made no difference. But yet the Stoics argued incessantly about this with the Peripatetics and Epicureans, and amused themselves with the inadmissible comparison of two wholly incommensurable quantities and with the contrary and paradoxical judgements arising therefrom, which they cast on one another. An interesting collection of these is afforded us from the Stoic side by the *Paradoxa* of Cicero.—from_The World as Will and Representation_. Translated from the German by E. F. J. Paye in two volumes: volume I, pp. 88-89 ”