One of the questions St. Thomas Aquinas posed in his short treatise on prayer (Summa Theologiæ, II-II, Q. 13, Art. 12) was, “Should prayer be vocal?” The answer is: Yes, if it increases our devotion.
Obviously, group prayer should be vocal. The priest at Mass must pray out loud so the faithful can know the prayers that are being offered, and so the faithful can respond appropriately according to the liturgy. People pray in unison at gatherings, such as on sidewalks in front of buildings where abortion ends the lives of babies. Families and friends pray together to bless meals. Parents pray out loud and ask their children to pray out loud for the purpose of instruction. Group prayers require us to actually say the words.
But what about individual prayer?
Prayer is an act of religion, and religion is a part of justice — the surrendering of our minds to God in reverence and praise. Since we cannot practice authentic justice without practicing authentic prudence, and since prudence demands that we first have to be honest with ourselves about our intent, whether to say prayers out loud or not when we are alone comes down to making a decision.
First (and again obviously), we do not pray out loud to tell God something He does not know. He knows what is in our hearts. Absolutely, we are not required to pray vocally as individuals.
But what if . . .
You are laying in bed or driving your car, and you just want to talk to God as your Father.
You are losing your temper with your children, and you are trying with all your might to stay calm, and you seek the peace of Christ before Whom you would be ashamed to indulge in such outburst.
You are suffering, and you need, with all your being, to cry out to the Holy Spirit for the grace that sustains you.
You are doing laundry, splitting firewood, or knitting a scarf, and you want to speak to Mary, your friend.
You are agonizing over a decision, and you need to ask a saint to pray for you.
. . . should you or should you not pray out loud?
Furthermore, why does it even matter to be asking this question?
Here’s why: St. Thomas advised that saying the words out loud can help us raise our minds to God. Prayer is first an act of reason and will, unique to rational creatures, an act of worship owed to God. Saying the words in addition to praying with our minds is like holding Rosary beads or burning incense. It is something extra to help us be attentive. And we are supposed to strive to pray attentively.
When we pray with our mind, we seek apprehension. “Apprehension” (apprehensionem) means to lay hold with the mind, to comprehend, to learn. We pray to learn the will of God. Therefore, prayer must begin with the assent of the mind. However, when we are alone, and when we choose to make our prayers vocal, we add to our effort to apprehend. We add an effort to show affection. “Affection” (affectionem) means to invoke an attitude of the mind toward something, a mental state brought about by an emotion or feeling. Voicing the prayer, in private as well as in public, is an exterior act that, as St. Aquinas put it, can excite an interior devotion. He quoted St. Augustine, “…by means of words and other signs we arouse ourselves more effectively to an increase of holy desires.”
Hence, voicing our prayers can be an effort to pay our debt to God. We praise Him not only with our mind, but also with our body, with our whole self, as if our love overflows out our mouths, and our voice tries to give breath to what our heart yearns to express. We pray out loud because we have an excess of passion. “Therefore,” as the psalmist said, “my heart hath been glad, and my tongue hath rejoiced.” —Psalm 15:9
Such abandon to passion is not always the case though. Voicing our prayers may not excite us internally. Indeed, moving our mouths and making sounds can distract us too. It is entirely possible, as St. Thomas, who was often found lifted in a state of ecstasy toward the end of his life, well knew, for a person’s interior devotion to be so strong that to voice the words would hinder the mind from its focus.
Words about other matters distract the mind and hinder the devotion of those who pray: but words signifying some object of devotion lift up the mind, especially one that is less devout.
St. Thomas also addressed that familiar scripture passage in Matthew 6, the one that says we are heathens if we do not pray in secret.
But thou when thou shalt pray, enter into thy chamber, and having shut the door, pray to thy Father in secret: and thy Father who seeth in secret will repay thee. And when you are praying, speak not much, as the heathens. For they think that in their much speaking they may be heard. —Matthew 6:6-7
If we are praying individually, but in the presence of others, we must be honest with ourselves. If we are praying to impress other people, praying just to be seen by others, then we are like those heathens Matthew wrote of in his Gospel. And we should not do that. If we are truly and honestly praying for the sake of apprehension and affection, then it matters not what other people think.
So if you pray alone, and you pray interiorly with strong devotion because you have accepted the grace that lifts you to grades of ecstasy, then pray as you were made to pray, blissfully, wonderfully nearer to God, knowing Him, loving Him, and serving Him with all of yourself. If you find that you are unable to keep your mind attentive, and if you discover that saying the prayerful words out loud lifts you to a stronger devotion, then trust that God smiles on that gift as well, for in our humility and obedience, and in our enthusiastic surrender, we become as children.