In His resurrection Christ, as the one grain of wheat, bore many grains (John 12:24). Through Christ's death and resurrection the one grain, Christ, became the many grains. When a single grain of wheat is sown into the earth, it grows and eventually produces many grains. In a sense, the original grain ceases to exist; it becomes the many grains. All the many grains together equal the original grain. Since Christ is in us, the many grains, He is wherever we are. Thus, He has become us. He is the aggregate grain, and we are the many grains produced by His resurrection.
The many grains produced by Christ's resurrection are His increase (John 3:30a). Farmers make a living by the increase of their seed. They sow a relatively small quantity of seed into the earth, and after three months they reap a large harvest. That harvest is the increase of the seed. When Jesus was on the earth traveling in the holy land, He was the unique grain. But today, consider how many "Christs" there are on this earth. There are not only thousands but millions around the globe. This is the vine mentioned in John 15. This great vine covers the entire globe. The church, which is Christ (1 Cor. 12:12) as His increase, is the true vine. This too is a product of Christ's resurrection. This is Christ's increase, propagation, and surplus.
The fourth stanza of Hymns, #203 reads:
We're Thy total reproduction,
Thy dear Body and Thy Bride,
Thine expression and Thy fulness
For Thee ever to abide.
We are Thy continuation,
Thy life-increase and Thy spread,
Thy full growth and Thy rich surplus,
One with Thee, our glorious Head.
In this verse a number of words are used to express the fact that the church is Christ's increase and expansion.
Furthermore, the many grains as the increase of Christ are the components of His Body, that is, the one bread, the church (Eph. 1:22-23; 1 Cor. 10:17). Every Lord's Day we take the Lord's table to participate in the bread. That bread signifies, first, Christ's physical body, which He gave up for us on the cross, and, second, Christ's mystical Body, which is the one bread, the church.