Prayer (15-16): Paul begins his prayer[1] for a people who already have every spiritual blessing.[2] And there is no doubt they possess it, since they have the marks of true conversion seen in their faith and love. In terms of their faith, they continue to trust the Lord Jesus and do not revert to their pagan beliefs.[3] As for their love, it continues to extend toward all the saints, not just their favorites in the church. In his prayer, he begins with thanksgiving, as usual, setting an example of godly thankfulness.[4] He also begins his prayer with accurate thoughts about the God to whom he prays.[5] He is "the God of our Lord Jesus Christ," high above even our master and Lord, and "the Father of glory.[6]" Paul prays with a clear view of both for whom and to whom he prays.
Understanding (17-18): Paul's prayer is that the saints would have a spirit[7] of wisdom (insight) and revelation (unveiling) in the knowledge of Him.[8] This is a prayer for understanding, not learned by rote or head-knowledge, but a perspective ("the eyes") in the core of one's being ("of your heart"). And we are to know the future hope for which God called us[9] and the value God places in us as His own "inheritance." God possesses us, and a marvelous future is up ahead. May our God help us see our part in His plans for His own glory (1:14)!
[1] This prayer extends to the end of the chapter. In the original, this is one long sentence, like the doxology.
[2] We already possess election, adoption, grace, redemption, forgiveness, knowledge of His will, etc. (1:3-14).
[3] Many from Ephesus converted in the past, and they did not revert to paganism (Acts 19:18-19, 26).
[4] Thanksgiving is part and parcel of the believer's life. Cf. 5:4, 20; Rom. 1:21; 2 Cor. 4:15; 1 Thess. 5:18.
[5] It is a sound approach to prayer to first consider who God is. Cf. Matt. 6:9-10; Isaiah 37:16-17.
[6] In His humanity, Jesus worships/prays to God (Mk. 15:34; Jn. 20:17). RE: God's glory cf. 1:6, 12, 14; Acts 7:2.
[7] NASB properly lowercases "spirit." This is not God the Holy Spirit since believers already have Him (1:13-14). This is the human spirit which needs God's enablement for a heart-perception of the blessings described.
[8] 1:18-19 identify the content of knowledge as centered around God, viz., His calling, inheritance and power.
[9] The calling has a forward expectation/hope for both us and God: our inheritance and His possession (1:14).