Charles H. Spurgeon on Psalms 115:14

The LORD shall increase you more and more, you and your children. Just as in Egypt he multiplied the people exceedingly, so will he increase the number of his saints upon the earth; not only shall the faithful be blessed with converts, and so with a spiritual seed; but those who are their spiritual children shall become fruitful also, and thus the multitude of the elect shall be accomplished; God shall increase the people, and shall increase the joy. Even to the end of the ages the race of true believers shall be continued, and shall increasingly multiply in number and in power. The first blessing upon mankind was, "Be fruitful, and multiply, and replenish the earth"; and it is this blessing which God now pronounces upon them that fear him. Despite the idols of philosophy and sacramentarianism, the truth shall gather its disciples, and fill the land with its defenders.