Else - (Ἐπεί Epei). Since; if this is not done; if what is said is not intelligible, how shall the unlearned be able appropriately to express his assent, and join in your devotions?
When thou shalt bless - When thou shalt bless God, or give thanks to him. If thou shalt lead the devotions of the people in expressing thanksgiving for mercies and favors. This may refer to a part of public worship, or to the thanks which should be expressed at table, and the invocation of the divine blessing to attend the bounties of his providence. Paul had illustrated his subject by prayer and by singing; be now does it by a reference to the important part of public worship expressed in giving thanks.
With the spirit - In the manner referred to above; that is, in an unknown tongue, in such a way that your own “heart” may be engaged in it, but which would be unintelligible to others.
He that occupieth the room - Is in the place, or the seat of the unlearned; that is, he who is unlearned. On the meaning of the word “room,” see the note at Luke 14:8. To “fill” a place means to occupy a station, or to be found in a slate or condition.
Of the unlearned - (τοῦ ἰδιώτου tou idiōtou. On the meaning of this word, see the note at Acts 4:13. Here it means one who was unacquainted with the foreign language spoken by him who gave thanks. It properly denotes a man in “private,” in contradistinction from a man in “public” life; and hence, a man who is ignorant and unlettered, as such people generally were.
Say Amen - This word means “truly, verily;” and is an expression of affirmation John 3:5 or of assent. Here it means assent. How can he pronounce “the” Amen; how can he express his assent; how can he join in the act of devotion? This “might” have been, and probably “was,” expressed aloud; and there is no impropriety in it. It “may,” however, be “mental” - a silent assent to what is said, and a silent uniting in the act of thanksgiving. In one way or the other, or in both, the assent should always be expressed by those who join in acts of public worship.