Like every potter he first of all makes the outlines in the clay. You may have seen a man at work executing designs in glass. Perhaps at the very first moment you may form a rough guess of what the whole thing is to be, though the ornament and elaboration which constitute the main part of the beauty you cannot yet discover.
Certain it is, that the moment a man begins to be prepared for heaven by the grace of God in his soul, you may see the outlines of what he is to be, although it is but the bare outlines. Shall I tell you what those outlines are? There is first of all in him—faith in Christ; a simple, child-like trust in him that did hang upon the tree. There is next in him another mark of the potter's hand—that is love to Christ—a love that is strong as death, though sometimes it seems to be feeble as a worm. There is in him also a hope that makes not ashamed, and a joy which makes glad his countenance. It is but the bare outline, as I have said, for the glory which excels is not there. The vase is only in its embryo, but yet sufficiently developed to give prophecy of its finished form; as for the pictures that shall be inlaid, as for all the many colors that shall be used on it, you cannot guess as yet, nor could you, unless you could climb to the potter's seat and see the plan upon which he looks as the clay revolves upon the wheel.
Dear brothers and sisters, have you anything in you as yet of the great outlines? Can you say in truth, "I believe on the Lord Jesus?" Fear not then, my hearer, you are a vessel of mercy.
— Charles Spurgeon
And He did so to make known the riches of His glory upon vessels of mercy, which He prepared beforehand for glory, even us, whom He also called, not from among Jews only, but also from among Gentiles. (Romans 9:23-24)Further Reading
The Veil is Not Rolled Up, but Rent
Resting in the Immutability of God
Christ is All