“When the natural road towards human fulfilment is blocked, human beings retreat into themselves, become involved in themselves, and try to create inwardly that world which some evil fate has denied them externally.If you cannot obtain from the world that which you really desire, you must teach yourself not to want it.If you cannot get what you want, you must teach yourself to want what you can get.This is a very frequent form of spiritual retreat in depth, into a kind of Inner Citadel, in which you try to lock yourself up against all the fearful ills of the world.”
It's a play off of a Marcus Aurelius concept I believe.