The desire Augustine saw in himself he also saw in all of us, a desire that brings a restlessness and thirst only satisfied at the fountain of true wisdom and everlasting love – Jesus Christ. 

“‘If anyone is thirsty, let him come to me and drink.’

  “The Lord himself, our God Jesus Christ, is the fountain of life; and he calls us to himself so that we may drink from him. Who will drink? Whoever loves; whoever is filled with the word of God; whoever adores enough, whoever desires enough; whoever is on fire with the love of wisdom.

  See the source from which that fountain flows. It comes from the same place that the manna came from in the wilderness – for the same person is both bread and fountain, Christ our Lord and God, for whom we should always hunger. Even if we eat him, the bread, with love, even if we devour him with desire, let us still hunger for him like starving people. So when we drink him, the fountain, let us always drink him with overflowing love, filled with longing and delighting in the gentle taste of his sweetness.

  For the Lord is gentleness and delight. We may eat and drink of him but still we will be hungry and thirst for more; for he is our food and drink that can never be entirely consumed. He can be eaten but there will always be more left. He can be drunk but he can never be drained dry. Our bread is eternal; our fountain lasts for ever, our fountain is sweet. 

So Isaiah says: come to the water all you who are thirsty – the fountain is for the thirsty, not for the surfeited. He calls the hungry and the thirsty to himself, and they can never drink enough: the more they drink, the more they desire to drink.

 Spiritual writers after Augustine took up the Augustine’s insights:

 If you are thirsty, drink from the fountain of life; if you are hungry, eat the bread of life. Blessed are they who hunger for that bread and thirst for that fountain; they eat and drink for ever and still they desire to eat and drink. For it is lovely above all things, that which is always eaten and drunk, always hungered and thirsted for. ‘Taste and see that the Lord is good.’”  St.Columbanus

The Church repeats his teaching in the prayer for his feast:

Renew in your Church, we pray, O Lord, the spirit with which you endowed your Bishop Saint Augustine

that, filled with the same spirit, we may thirst for you, the sole fount of true wisdom,and seek you, the author of heavenly love.

Through our Lord Jesus Christ, your Son, who lives and reigns with you in the unity of the Holy Spirit, God, for ever and ever. Amen