Jamieson, Fausset & Brown

And--And therefore; and so. Translate in the Greek order, "Ye are in Him (by virtue of union with Him) filled full" of all that you need (Joh 1:16). Believers receive of the divine unction which flows down from their Divine Head and High Priest (Psa 133:2). He is full of the "fulness" itself; we, filled from Him. Paul implies, Therefore ye Colossians need no supplementary sources of grace, such as the false teachers dream of. Christ is "the Head of all rule and authority" (so the Greek), Eph 1:10; He, therefore, alone, not these subject "authorities" also, is to be adored (Col 2:18).