17. The value of prayer comes from the thought to which it is united. So it is impossible to join any thought to something that is not understood, since what is not understood cannot touch the heart. For the great majority of human beings prayers that are said in an unknown language are nothing more than a conglomeration of words which say nothing to the Spirit. In order for prayer to touch one, it is necessary for each word to awaken an idea, and when the words are not comprehended they are unable to do this. It would be merely a simple formula, whose virtue depended on the greater or lesser number of times it was repeated. Many pray from duty, others from obedience to habit; this is why they judge themselves to be exonerated from their duty after having prayed a determined prayer a sufficient number of times, in a certain order. God reads what passes deep in our hearts. He scrutinizes our thought and our sincerity; therefore in judging Him to be more sensitive to the format rather than the depth is to discredit Him (See chapter 28, item 2).