St. Teresa of Avila on prayer.

Passage

As far as I can understand, the gate by which to enter this castle is prayer and meditation. I do not allude more to mental than to vocal prayer, for if it is prayer at all, the mind must take part in it. If a person neither considers to Whom he is addressing himself, what he asks, nor what he is who ventures to speak to God, although his lips may utter many words, I do not call it prayer. Sometimes, indeed, one may pray devoutly without making all these considerations through having practiced them at other times. The custom of speaking to God Almighty as freely as with a slave — caring nothing wether the words are suitable or not, but simply saying the first thing that comes to mind from being learnt by rote by frequent repetition — cannot be called prayer: God grant that no Christian may address Him in this manner.