A contented spirit is like a watch: though you carry it up and down with you yet the spring of it is not shaken, nor the wheels out of order, but the watch keeps its perfect motion; so it was with St. Paul, though God carried him into various conditions, yet he was not lift up with the one, nor cast down with the other; the spring of his heart was not broken, the wheels of his affections were not disordered, but kept their constant motion towards heaven, still content.

from The Art of Divine Contentment