For what man knoweth the things of a man, save the spirit of man which is in him? even so the things of God knoweth no man, but the Spirit of God. – 1 Corinthians 2:11

How hard it is sometimes to state a fact which you perfectly understand yourself, in such a way that another man may see it. It is like the telescope; there are many persons who are disappointed with a telescope, because whenever they walk into an observatory and put their eye to the glass, expecting to see the rings of Saturn, and the belts of Jupiter, they have said, “I can see nothing at all; a piece of glass, and a grain or two of dust is all I can see!” “But,” says the astronomer, when he comes, “I can see Saturn in all her glory.” Why cannot you? Because the focus does not suit the stranger’s eye. By a little skill, the focus can be altered so that the observer may be able to see what he could not see before. So is it with language; it is a sort of telescope by which I enable another to see my thoughts, but I cannot always give him the right focus. Now the Holy Spirit always gives the right focus to every truth. He sheds a light so strong and forcible upon the Word, that our spirit says. “Now I see it, now I understand it.” For even here, in this precious Book, there are words which I have looked at a hundred times, but I could not understand them, till at some favored hour, the key-word seemed as if it leaped up from the midst of the verse and said to me, “Look at the verse in My light,” and at once I perceived-not always from a word in the verse itself, but sometimes in the context-I perceived the meaning which I could not see before. This, too, is a part of the Spirit’s training-to shed a light upon truth. But the Spirit not only enlightens the truth, but He enlightens the understanding. ‘Tis marvellous, too, how the Holy Ghost does teach men who seemed as if they never could learn…The Spirit teaches us by enlightening the understanding. ~ C.H. Spurgeon

https://www.blueletterbible.org/Comm/spurgeon_charles/sermons/0315.cfm