If you avoid only the things under your control that are against Nature, you will not fall into anything that you wish to avoid. But if you try to avoid disease, death or poverty, you will experience misfortune. Remove, therefore, your aversion from all that is not under your control, and apply it the things against Nature within your control.
Disease, death, poverty, and the countless other horrible sounding words that terrify most people are things indifferent to the Stoic. They are inevitable and perfectly natural. They are neither evil nor good. They simply are. Moreover, they are completely outside of the realm of our control. Our ability, by contrast, to choose what we reject or avoid is wholly within our control.
It is a type of madness to exercise our power of aversion against the natural and inevitable, and to desire the impossible. If we do so, we will surely and frequently experience misfortune, as our aversion is towards things that must necessarily occur.
The person who experiences misfortunes and grief suffers it needlessly. Worse still, he suffers it through his own doing. He has set his aversion against the wrong objects, mistaking them for evils. Vice alone is evil and unnatural. And Vice is very much within the sphere of our control. If a man wishes to avoid Vice and only Vice, misfortune will be far from him.