If men will not receive the Truth of God till they understand it, there are many things which they will never receive. Yes, there are many facts, common facts in Nature, which nobody would deny but a fool—which yet must be denied if we will not believe them till we understand them! There is a fish fresh taken from the sea—you take it to the cook to serve it on the table. You eat salt with it, do you? What for? You will have it dried and salted, but what for? Did not it always live in the salt sea? Why then is it not salt? It is as fresh as though it had lived in the purling brooks of the upland country—not a particle of salt about it—yet it has lived wholly in the salt sea! Do you understand that? No, you cannot. But there it is, a fresh fish in a salt sea!
And yonder are an ox and a sheep, and they are eating in the same meadow, feeding precisely on the same food. But the grass in one case turns to beef, in the other case to mutton—and on one animal there is hair and on the other wool. How is that? Do you understand it? So there may be two great Truths in Scripture, which are both Truths of God and yet all the wise men in the world might be confused to bring those two Truths together. I do not understand, I must confess, why Moses was told to cut down a tree and put it in the bitter waters of Marah. I cannot see any connection between a tree and the water, so that the tree should make it sweet, but yet I do believe that when Moses put the tree into the water the bitterness of Marah departed and the stream was sweet. I do not know why it is that Elisha, when he went to Jericho, and found the water the bitterness of Marah departed and the stream was sweet.
I do not know why it is that Elisha, when he went to Jericho, and found the water nauseous, said, “Bring me a cruse of salt.” I do not know why his putting the salt into the stream should make it sweet—it looks to me as if it would operate the other way—but I believe the miracle, namely, that the salt was put in and that it was sweetened. So I do not understand how it is that my bidding impenitent sinners to repent should in any way be likely to make them do so, but I know it does—I see it every day. I do not know why a poor weak creature saying to his fellow men, “Believe,” should lead them to believe, but it does so—and the Holy Spirit blesses it—and they do believe and are saved! And if we cannot see how, if we see the fact, we will be content and bless God for it!
— Charles H. Spurgeon, Apostolic Exhortation #804, delivered April 5, 1868 at the Metropolitan Tabernacle, London.