In the Greek text Ephesians 1:3-14 are one sentence. The Holy Spirit carried Paul along in his thinking as he contemplated God"s provision so that he moved quickly from one blessing to the next. It is as though he was ecstatically opening a treasure chest, lifting its jewels with his hands, letting them cascade through his fingers, and marveling briefly at them as they caught his eye. [source][source][source]
"Each section ends with a note of praise for God ( Ephesians 1:6; Ephesians 1:11; Ephesians 1:14), focusing on a different member of the Trinity. After an opening summary of all the saints" spiritual blessings ( Ephesians 1:3), the first section ( Ephesians 1:4-6) offers up praise that the Father has chosen us in eternity past; the second section ( Ephesians 1:7-11) offers up praise that the Son has redeemed us in the historical past (i.e, at the cross); the third section ( Ephesians 1:12-14) offers up praise that the Holy Spirit has sealed us in our personal past, at the point of conversion." [1][source]
"Normally, after the greeting Paul gives an introductory thanksgiving for the recipients of the letter. In this epistle he changes the order, for before he gives his thanksgiving in Ephesians 1:15-23, he has in Ephesians 1:3-14 a paean of praise for what God has done for the believer." [2][source]
". . . Ephesians 1:3-14 is one of the longest psalms of the New Testament, and it is a praise psalm in its form." [3][source]