6 But what then has the Church of God to do, that it may be able to understand what it has first obtained grace to believe? It must make the mind capacious for receiving what shall be given it. And that this may be done, that the mind, that is, may be capacious, our Lord God suspends His promises, He has not taken them away. Therefore does He suspend them, that we may stretch out ourselves; and therefore do we stretch ourselves out, that we may grow; and therefore do we grow, that we may reach them.
Behold the Apostle Paul stretching himself out unto these suspended promises: “Not as though I had already attained, either were already perfect. Brethren, I count not myself to have apprehended: but this one thing I do; forgetting those things which are behind, and stretching forth unto those things which are before, I press earnestly toward the mark for the prize of the high calling of God in Christ Jesus.” He was running on the earth; the prize hung suspended from heaven. He ran then on the earth; but in spirit he ascended. Behold him thus stretching himself out, behold him hanging forth after the suspended prize. “I press on,” he says, “for the prize of the high calling of God in Christ Jesus.”
Source: Sermons on Selected Lessons of the New Testament (New Advent)