IV. The love of God is fostered by good works
This state of mind, therefore, beloved, from which earthly love is excluded, is strengthened by the habit of well-doing, because the conscience must needs be delighted at good deeds, and do willingly what it rejoices to have done. Thus it is that fasts are kept, alms freely given, justice maintained, frequent prayer resorted to, and the desires of individuals become the common wish of all. Labour fosters patience, gentleness extinguishes anger, loving-kindness treads down hatred, unclean desires are slain by holy aspirations, avarice is cast out by liberality, and burdensome wealth becomes the means of virtuous acts. But because the snares of the devil are not at rest even in such a state of things, most rightly at certain seasons of the year the renewal of our vigour is provided for: and now in particular, when one who is greedy of present good might boast himself over the clemency of the weather and the fertility of the land, and having stored his crops in great barns, might say to his soul, “you have much goods, eat and drink,” let him take heed to the rebuke of the Divine voice, and hear it saying, “You fool, this night they require your soul of you, and the things which you have prepared, whose shall they be?” This should be the wise man's most anxious consideration, in order that, as the days of this life are short and its span uncertain, death may never come upon him unawares, and that knowing himself mortal he may meet his end fully prepared. And so, that this may avail both for the sanctification of our bodies and the renewal of our souls, on Wednesday and Friday let us fast, and on Saturday let us keep vigil with the most blessed Apostle Peter, whose prayers will help us to obtain fulfilment of our holy desires through Christ our Lord, Who with the Father and the Holy Ghost lives and reigns for ever and ever. Amen.
Source: Sermons (New Advent)