Luke 17:7

the design and end of this parable is to shew that, rigorously speaking, we are useless servants with regard to God. This sovereign Master has a right to exact of us every kind of service, and to make us apply ourselves to any task he might think proper, without our having any reason to complain either of the difficulty, trouble, or length of our labours; we are entirely his, and he is master of our persons, time, and talents. We hold of him whatever we possess, and woe to us if we abuse his trust, by applying our talents to any use contrary to his designs. But though he be Lord and Master, he leaves our liberty entire. If he produces in us holy desires, if he works in us meritorious actions, gives us virtuous inclinations and supernatural gifts, he sets to our account the good use we make of them; and in crowning our merits, he crowns his own gifts. (St. Augustine, lib. ix. Confes. and Serm. 131.) (Calmet)