(1) Israel is guilty (v. 18). Someone might have argued with Paul: “But how do you know that Israel really heard?” His reply would have been Psalm 19:4, a psalm that emphasizes the revelation of God in the world. God reveals Himself in creation (Ps. 19:1-6) and in His Word (Ps. 19:7-11). The “book of Nature” and the “book of Revelation” go together and proclaim the glory of God. Israel had the benefit of both books, for she saw God at work in nature, and she received God’s written Word. Israel heard, but she would not heed. No wonder Jesus often had to say to the crowds, “He that hath ears to hear, let him hear” (Matt. 11:15; Mark 4:9).