Else if thou bless with the spirit (επε εαν ευλογηις εν πνευματ). Third class condition. He means that, if one is praying and praising God (1. Corinthians 10:16) in an ecstatic prayer, the one who does not understand the ecstasy will be at a loss when to say "amen" at the close of the prayer. In the synagogues the Jews used responsive amens at the close of prayers (Nehemiah 5:13; Nehemiah 8:6; 1. Chronicles 16:36; Psalm 106:48).

He that filleth the place of the unlearned (ο αναπληρων τον τοπον του ιδιωτου). Not a special part of the room, but the position of the ιδιωτου (from ιδιος, one's own), common from Herodotus for private person (Acts 4:13), unskilled (2. Corinthians 11:6), uninitiated (unlearned) in the gift of tongues as here and verses 1. Corinthians 14:23.

At thy giving of thanks (επ τη ση ευχαριστια). Just the prayer, not the Eucharist or the Lord's Supper, as is plain from verse 1. Corinthians 14:17.