Quoted in the reflections from para. 35 of the Encyclical:
There are times when the burden of need and our own limitations might tempt us to become discouraged. But precisely then we are helped by the knowledge that, in the end, we are only instruments in the Lord’s hands; and this knowledge frees us from the presumption of thinking that we alone are personally responsible for building a better world. In all humility we will do what we can, and in all humility we will entrust the rest to the Lord. It is God who governs the world,
not we. We offer him our service only to the extent that we can, and for as long as he grants us the strength.
Quoted in the reflections from para. 35 of the Encyclical: