God has the only key of the soul. We can shut our souls, but cannot open them again. So we can shut our hearts to divine truths. We can naturally do this. But to open them without the help of the Spirit we cannot do. He can open our understandings, as He did the disciples’.

He can open our hearts to believe. He can do, and He will do it. If we seek to Him, He will not put back the humble desires of them that fear Him. And therefore for the heavenly light and heavenly revelation, all the teaching of the men of the world cannot do it.

If we know no more than we have by books, and men that teach us, we shall never come to heaven. But we must have God teach the heart, as well as the brain. He must teach not only the truths themselves, as they be discovered, but the love of them, the faith of them, the practice of them.

And only He can do this, He only can teach the heart, He only can discover the bent of the heart, and Satan’s wiles that cast a cloud upon the understanding. Only the Spirit can do it.

And therefore, in all our endeavors, labor to get knowledge, and join holiness and divine grace, and pray to God that He would reveal the mystery of salvation to us.

—Richard Sibbes, in The Glorious Feast of the Gospel