You do not, however, mean that the tongue is quite useless in prayer?

Not at all, for sometimes it helps the mind, sustaining and keeping it from being drawn away from God so easily. Besides, since more than all the other members it was formed to the glory of God, it is very reasonable that it should be employed by all means for this purpose. Moreover, the zeal of the heart by its own ardour and vehemence often constrains the tongue to speak quite spontaneously.