Because we do not always see these seeds growing, we need an interior certainty, a conviction that God is able to act in every situation, even amid apparent setbacks: “We have this treasure in earthen vessels” (2 Cor 4:7). This certainty is often called “a sense of mystery”. It involves knowing with certitude that all those who entrust themselves to God in love will bear good fruit (cf. Jn 15:5). This fruitfulness is often invisible, elusive and unquantifiable.
We can know quite well that our lives will be fruitful, without claiming to know how, or where, or when. We may be sure that none of our acts of love will be lost, nor any of our acts of sincere concern for others. No single act of love for God will be lost, no generous effort is meaningless, no painful endurance is wasted. All of these encircle our world like a vital force. Sometimes it seems that our work is fruitless, but mission is not like a business transaction or investment, or even a humanitarian activity. It is not a show where we count how many people come as a result of our publicity; it is something much deeper, which escapes all measurement. It may be that the Lord uses our sacrifices to shower blessings in another part of the world which we will never visit. The Holy Spirit works as he wills, when he wills and where he wills; we entrust ourselves without pretending to see striking results. We know only that our commitment is necessary. Let us learn to rest in the tenderness of the arms of the Father amid our creative and generous commitment. Let us keep marching forward; let us give him everything, allowing him to make our efforts bear fruit in his good time.
— From Evangelii Gaudium, “The Joy of the Gospel.” by Pope Francis