"Among the older records, we find chapter after chapter of which we can read the characters, and make out their meaning: and as we approach the period of man's creation, our book becomes more clear, and nature seems to speak to us in language so like our own, that we easily comprehend it. But just as we begin to enter on the history of physical changes going on before our eyes, and in which we ourselves bear a part, our chronicle seems to fail us-a leaf has been torn out from nature's record, and the succession of events is almost hidden from our eyes."