Whenever I speak of prayer, I seem to hear expressed in your hearts some human thoughts that I have also heard frequently from others and sometimes experienced in my own heart. Why is it, seeing that we never cease from prayer, that scarcely does any one of us seem to experience the fruit of his prayer? As we come to prayer, so we return; no one responds to us, no one gives us anything, but we seem to have labored in vain.
But what does the Lord say in the Gospel? Do not judge by appearance, he says, but judge with right judgment. What is right judgment but the judgment of faith? The one made righteous by faith lives. Follow the judgment of faith, then, and not your own experience, since faith is true but experience is false. What is the truth of faith if not what the Son of God promises: Whatever you ask for in prayer, believe that you will receive it, and it will come to you?
None of you should think his prayer is of small account. I tell you that he to whom we pray does not think it of small account. Before it has left your mouth he has ordered it written in his book. Unquestionably we can hope for one of two things: that he will grant either what we ask, or what he knows is better for us. We do not know what to pray for as we ought, but he has pity on our ignorance. He accepts our prayer in his goodness, but he does not give us what is not expedient for us or what we should not be given so quickly. Therefore, our prayer will not be fruitless.
Bernard of Clairvaux, Sermon Five for Lent, CF 52, pp 45-46