The cucumber is bitter? Then throw it out.

There are brambles in the path? Then go around them.

That’s all you need to know. Nothing more. Don’t demand to know “why such things exist.”

Marcus Aurelius, Meditations 8:50

This quote is basically an extension of the “none of your business” philosophy that’s prevalent in Stoicism (see my post on that here). It’s also another good example of not worrying about things that are not within your control.

Don’t get yourself involved in negative things. If there are problems that you don’t need to be worrying about, then walk away from them or around them. And definitely don’t be fretting about why bad things exist. That’s the world we live in.