In my post on what to do before starting spiritual direction, I link to this excerpt from Peter Thomas Rohrbach, In Conversation with Christ, one of the great, practical guides to prayer:
BEFORE EMBARKING on our discussion of the practice of mental prayer, it would be well to pause and examine the motive for meditating. Why do spiritual writers place so much insistence upon the practice of meditation? Is it an integral part of the spiritual life; or is it a superfluous nicety of spiritual esthetes? To answer the question let us call on two saints of the Church, St. Alphonsus and St. Teresa. St. Alphonsus stoutly maintains: It is morally impossible for him who neglects meditation to live without sin. St. Teresa corroborates his statement in these words: He who neglects mental prayer needs not a devil to carry him to hell, but he brings himself there with his own hands. We can readily ascertain that meditation in the mind of these two saints is no superfluous nicety, it is a basic necessity for spiritual living. Nor is this insistence on mental prayer merely a pet theory of theirs. They reflect the traditional doctrine of the Church. In our own day, Pope Pius XII has paused twice in his encyclicals to remind us of the value of meditation: It must be stated without reservation that no other means has the unique efficacy of meditation, and that as a consequent, its daily practice can in no wise be substituted for. The case for meditation can be easily proved. Christ came to earth to re-establish God’s friendship with man— “I call you now not servants, but friends.”
Our Lord Himself has made the initial overture in this friendship; we must, on our part, reciprocate, and strive to maintain the companionship at its highest level. This entails a sustained contact with Christ; and prayer is our principal contact with Him. However, vocal prayer does not completely fulfill this need—we are required to employ the language of the Church’s official prayers, but we must also converse with God in sentiments which arise from our own hearts and are expressed in our own words. As St. Teresa comments: Take my advice and let no one mislead you by pointing out any other way than prayer. I am not discussing here whether mental and vocal prayer are necessary for everybody; but I contend that you require both. There is serious danger in restricting our prayer life to vocal prayer: we stand the risk of becoming victims of that vicious habit of sing-songing our prayers without actually contacting Christ. Furthermore, the true lover wishes to express his affection in his own words, and not rely on the “canned” sentiments of a spiritual writer. In meditation the soul is forced, as it were, to speak directly with Christ; there can be no hiding behind standardized formulae of prayer. And this is the way the truly spiritual man would want it: an opportunity to speak privately with Christ about the many affairs of his daily life. The experience of the saints has demonstrated that an amazing change occurs in one’s life when he forms the daily habit of intimate, heart-to-heart conversation with Christ…
Meditation, then, effects a complete change in a person’s life, and adds a new tone to all his activities. The author recalls a conversation some years ago with a woman who had undertaken in earnest the practice of mental prayer. This devout lady, previously much occupied with the “things of the day,” confided: “Those things which formerly interested me just don’t seem to matter much anymore.” Our Lord had given her a taste of His intimate friendship, and all else seemed insipid…
Meditation, naturally, consumes time. But this is not time lost; rather, the time expended in meditation aids in the ultimate conservation of time. This is true, first of all, because it places the soul under the direct influence of Christ, Who will then take complete charge of a person’s activities. And, further, the added perspective gained in meditation will enable one to better regulate his life by the separation of the non-essential from the essential. Dom Chautard, in his magnificent book, Soul of the Apostolate, relates this enlightening incident: One of our great bishops, overburdened with his duties, explained this to a statesman, who also had too much to do. The latter had asked the bishop the secret of his constant work. “My dear friend,” said the bishop, “add to your other occupations half an hour’s meditation every morning. Not only will you get through your business, but you will find time for still more.”Without this daily period of meditation, the entire spiritual life stands in danger. Is this perhaps the reason that our Blessed Mother in her program of reparation inaugurated at Fatima has requested fifteen minutes meditation every first Saturday? At any rate, Pope Pius XII assures us that “no other means has the unique efficacy of meditation, and that as a consequence its daily practice can in no wise be substituted for.”
…St. Teresa presents us a crystal-clear picture of meditation: the mind furnishing matter for the heart’s talk with Christ. And, above all, her fundamental rule that prayer consists not in thought, but in love.