Everything that isn't us must be an incidental to us.

Just as on a voyage, when your ship has anchored, if you should go on shore to get fresh water, you may pick up a small shell-fish or little bulb on the way, but you have to keep your attention fixed on the ship, and turn about frequently for fear lest the captain should call; and if he calls, you must give up all these things, if you would escape being thrown on board all tied up like the sheep. So it is also in life: If there be given you, instead of a little bulb and a small shell-fish, a little wife and child, there will be no objection to that; only, if the Captain calls, give up all these things and run to the ship, without even turning around to look back. And if you are an old man, never even get very far away from the ship, for fear that when He calls you may be missing.