From a sermon by Saint Leo the Great, pope

In the gospel of John the Lord says: In this will all men know that you are my disciples, if you have love for each other. In a letter of the same apostle we read: Beloved, let us love one another, for love is from God, and everyone who loves is born of God and knows God; he who does not love does not know God, for God is love.
The faithful should therefore enter into themselves and make a true judgment on their attitudes of mind and heart. If they find some store of love’s fruit in their hearts, they must not doubt God’s presence within them. If they would increase their capacity to receive so great a guest, they should practice greater generosity in doing good, with persevering charity.
If God is love, charity should know no limit, for God cannot be confined.
Any time is the right time for works of charity, but these days of Lent provide a special encouragement. Those who want to be present at the Lord’s Passover in holiness of mind and body should seek above all to win this grace, for charity contains all other virtues and covers a multitude of sins.
As we prepare to celebrate that greatest of all mysteries, by which the blood of Jesus Christ did away with our sins, let us first of all make ready the sacrificial offerings of works of mercy. In this way we shall give to those who have sinned against us what God in his goodness has already given us.
Let us now extend to the poor and those afflicted in different ways a more open-handed generosity, so that God may be thanked through many voices and the relief of the needy supported by our fasting. No act of devotion on the part of the faithful gives God more pleasure than that which is lavished on his poor. Where he finds charity with its loving concern, there he recognizes the reflection of his own fatherly care.
In these acts of giving do not fear a lack of means. A generous spirit is itself great wealth. There can be no shortage of material for generosity where it is Christ who feeds and Christ who is fed. In all this activity there is present the hand of him who multiplies the bread by breaking it, and increasing it by giving it away.
The giver of alms should be free from anxiety and full of joy. His gain will be greatest when he keeps back least for himself. The holy apostle Paul tells us: He who provides seed for the sower will also provide bread for eating; he will provide you with more seed, and will increase the harvest of your goodness, in Christ Jesus our Lord, who lives and reigns with the Father and the Holy Spirit for ever and ever. Amen.