Millstones and Pledges.

Ephesians 1:13-14 Amplified Bible (AMP) In Him you also who have heard the Word of Truth, the glad tidings (Gospel) of your salvation, and have believed in and adhered to and relied on Him, were stamped with the seal of the long-promised Holy Spirit. That [Spirit] is the guarantee of our inheritance [the firstfruits, the pledge and foretaste, the down payment on our heritage], in anticipation of its full redemption and our acquiring [complete] possession of it—to the praise of His glory.