In early times, no one would take "day" to mean anything else but an earth day of the ordinary kind, and no one would question whether or not the whole existing animals and plants, or their ancestors, appeared on earth in six such days, or whether anything else was meant. Again, by the time St. Augustine was writing, a little more knowledge of nature and a little more habit of reasoning about the origin of things was in the world, and that knowledge led people to suppose that creation meant only the making of things "out of nothing," but that it would take longer than six times twelve hours, so that "days" might mean "periods." And people imagined for a long time that--taking for an example the work in the middle of the narrative--there was a time when the earth emerged from the tumult of waters, that it then got covered with plants, the waters remaining barren of life; but that when the plants had come up all over the ground, then the waters all at once became full of all sorts of sea-shells, fish, and monsters of the deep, and so on. They did all this, by naturally _assuming_ that the terms "creation," "day," &c., meant what the _existing state of knowledge_ at the time suggested. At the present day, one would have supposed that every one must feel that while the term "day" might or might not admit of explanation, certainly _creation_ (i.e., terms implying it) did require very great care in interpreting, and very great consideration as to what they really meant But however that may be, we have here a passage which _must_ have an explanation; and which must have an explanation that depends on the state of knowledge. The utility of Revelation is not negatived by this necessary result of the employment of human language in describing the facts. It was _not_ necessary before, that all should be understood; it may be now increasingly necessary in the purposes of God that it should be. At any rate the fact is so, that in former days people did not possess the data for knowing fully what creation meant, and certainly they do now possess it to a very much greater extent at least. Always men could learn from the narrative what it always was important for them to learn, namely, God's Sovereignty and Authorship. It is in this way that the value of the _general_ teaching of the narrative comes out, and not by trying to allow a mixture of truth and falsehood in Revelation. All is and always was true; but _all_ the truth was not equally extractable at all times. Again: the dignity of the old written Revelation is not compromised because God has virtually given a further revelation in His works, i.e., by enabling man to know more about the rock-strata and the succession of life on the earth. That is what it really comes to. It should never be forgotten that the book of Nature _is_ a revelation.