The genesis of this book lies in the same conflict and interaction of metaphors—arrows of history and cycles of immanence—that fueled the discovery of deep time in geology. If I have succeeded in conveying the intended order of my thoughts, this book may strike readers as forged to some unity in a rational manner—as a product, in other words, of immanent structure reflected in the metaphor of time's cycle. But such a view, while reflecting (I hope) the logic of construction, would grossly misrepresent the psychologic of origin, for this volume is cobbled together from bits and pieces of time's arrow, quirky and unpredictable moments of my own contingent history. Tiny events that seemed meaningless at the time are horseshoe nails in the final structure. I cannot begin to specify all these incidents of "just history." My father took me to see a Tyrannosaurus when I was five. George White, great gentleman and bibliophile, gave me a seventeenth-century edition of Burnet's Tdluris theoria sacra in lieu of an honorarium for a talk. John Lounsbury illustrated uniformitarianism by an example that conflated distinct meanings during an introductory course in geology at Antioch College. I knew that something was wrong, but didn't understand what, until I studied David Hume on induction. I visited the Portrush Sill in Northern Ireland on a spring field course at the University of Leeds (during an undergraduate year abroad), and saw the dichotomy of neptunism and plutonism etched in rocks. I stood in mixed horror and fascination before the skeleton(s) of Ritta-Christina, the Siamese twin girls of Sardinia, in a Paris museum. I perceived Burnet's frontispiece in the glittering beauty of