A.T. Robertson Commentary Ephesians 1:10

"unto a dispensation of the fulness of the times, to sum up all things in Christ, the things in the heavens, and the things upon the earth; in him, [I say,]" — Ephesians 1:10 (ASV)

Unto a dispensation of the fulness of the times (εις οικονομιαν του πληρωματος των καιρων). See Col 1:25 for οικονομιαν. In Ga 4:4 "the fulness of the time" (το πληρωμα του χρονου) the time before Christ is treated as a unit, here as a series of epochs (καιρων). Cf. Mr 1:15; Hebrews 1:1. On πληρωμα see also Ro 11:26; Ephesians 3:19; 4:13.

To sum up (ανακεφαλαιωσασθα). Purpose clause (amounting to result) with first aorist middle infinitive of ανακεφαλαιοω, late compound verb ανα and κεφαλαιοω (from κεφαλαιον, Hebrews 8:1, and that from κεφαλη, head), to head up all things in Christ, a literary word. In N.T. only here and Ro 13:9. For the headship of Christ in nature and grace see Col 1:15-20.