7. It is similar for lifeless things that make a sound, like a flute or harp. Unless they make a distinction in the notes, how can what is played on the flute or harp be understood?
8. If, for example, the trumpet makes an unclear sound, who will get ready for battle?
9. It is the same for you. If you do not speak clearly with your tongue, how will anyone know what is being said? For you will be speaking into the air.
10. There are probably many kinds of languages in the world, and none is without meaning.
11. If then I do not know the meaning of a language, I will be a foreigner to the speaker and the speaker a foreigner to me.
12. It is the same with you. Since you are eager for manifestations of the Spirit, seek to abound in order to strengthen the church.
13. So then, one who speaks in a tongue should pray that he may interpret.
14. If I pray in a tongue, my spirit prays, but my mind is unproductive.
15. What should I do? I will pray with my spirit, but I will also pray with my mind. I will sing praises with my spirit, but I will also sing praises with my mind.
16. Otherwise, if you are praising God with your spirit, how can someone without the gift say “Amen” to your thanksgiving, since he does not know what you are saying?
17. For you are certainly giving thanks well, but the other person is not strengthened.
18. I thank God that I speak in tongues more than all of you,
19. but in the church I want to speak five words with my mind to instruct others, rather than ten thousand words in a tongue.
20. Brothers and sisters, do not be children in your thinking. Instead, be infants in evil, but in your thinking be mature.
21. It is written in the law: “By people with strange tongues and by the lips of strangers I will speak to this people, yet not even in this way will they listen to me,” says the Lord.