(_a_) Natural theology.—The universe is a source of theology. The Scriptures assert that God has revealed himself in nature. There is not only an outward witness to his existence and character in the constitution and government of the universe (Ps. 19; Acts 14:17; Rom. 1:20), but an inward witness to his existence and character in the heart of every man (Rom. 1:17, 18, 19, 20, 32; 2:15). The systematic exhibition of these facts, whether derived from observation, history or science, constitutes natural theology. Outward witness: _Ps.19:1-6—_“The heavens declare the glory of God”; _Acts 14:17—_“he left not himself without witness, in that he did good, and gave you from heaven rains and fruitful seasons”; _Rom. 1:20—_“for the invisible things of him since the creation of the world are clearly seen, being perceived through the things that are made, even his everlasting power and divinity.” Inward witness: _Rom. 1:19—τὸ γνωστὸν τοῦ Θεοῦ = _“that which is known of God is manifest in them.” Compare the ἀποκαλύπτεται of the gospel in verse 17, with the ἀποκαλύπτεται of wrath in verse 18—two revelations, one of ὀργή, the other of χάρις; see Shedd, Homiletics, 11. _Rom. 1:32—_“knowing the ordinance of God”; _2:15—_“they show the work of the law written in their hearts.” Therefore even the heathen are “without excuse”_ (Rom. 1:20)_. There are two books: Nature and Scripture—one written, the other unwritten: and there is need of studying both. On the passages in Romans, see the Commentary of Hodge. Spurgeon told of a godly person who, when sailing down the Rhine, closed his eyes, lest the beauty of the scene should divert his mind from spiritual themes. The Puritan turned away from the moss-rose, saying that he would count nothing on earth lovely. But this is to despise God’s works. J. H. Barrows: “The Himalayas are the raised letters upon which we blind children put our fingers to spell out the name of God.” To despise the works of God is to despise God himself. God is present in nature, and is now speaking. _Ps. 19:1—_“The heavens declare the glory of God, and the firmament showeth his handiwork”—present tenses. Nature is not so much a _book_, as a _voice_. Hutton, Essays, 2:236—“The direct knowledge of spiritual communion must be supplemented by knowledge of God’s ways gained from the study of nature. To neglect the study of the natural mysteries of the universe leads to an arrogant and illicit intrusion of moral and spiritual assumptions into a different world. This is the lesson of the book of Job.” Hatch, Hibbert Lectures, 85—“Man, the servant and interpreter of nature, is also, and is thereby, the servant and interpreter of the living God.” Books of science are the record of man’s past interpretations of God’s works.