From St. Teresa of Avila's Way of Perfection.
Let us now return to our vocal prayer, so that we may learn to pray in such a way that, without our understanding how, God may give us everything at once: if we do this, as I have said, we shall pray as we ought. As you know, the first things must be examination of conscience, confession of sin and the signing of yourself with the Cross. Then, daughter, as you are alone, you must look for a companion -- and who could be a better Companion than the very Master Who taught you the prayer that you are about to say? Imagine that this Lord Himself is at your side and see how lovingly and how humbly He is teaching you -- and, believe me, you should stay with so good a Friend for as long as you can before you leave Him. If you become accustomed to having Him at your side, and if He sees that you love Him to be there and are always trying to please Him, you will never be able, as we put it, to send Him away, nor will He ever fail you. He will help you in all your trials and you will have Him everywhere. Do you think it is a small thing to have such a Friend as that beside you?
O sisters, those of you whose minds cannot reason for long or whose thoughts cannot dwell upon God but are constantly wandering must at all costs form this habit. I know quite well that you are capable of it -- for many years I endured this trial of being unable to concentrate on one subject, and a very sore trial it is. But I know the Lord does not leave us so devoid of help that if we approach Him humbly and ask Him to be with us He will not grant our request. If a whole year passes without our obtaining what we ask, let us be prepared to try for longer. Let us never grudge time so well spent. Who, after all, is hurrying us? I am sure we can form this habit and strive to walk at the side of this true Master.