If all the parts of the universe have been so appointed that they could neither be better adapted for use nor be made more beautiful in appearance . . . If, then, nature’s attainments transcend those achieved by human design, and if human skill achieves nothing without the application of reason, we must grant that nature too is not devoid of reason.

Cicero was also the first to invoke the clock-maker metaphor that later became the touchstone argument in favor of an “intelligent designer.” In Cicero’s words:

It can surely not be right to acknowledge as a work of art a statue or a painted picture, or to be convinced from distant observations of a ship’s course that its progress is controlled by reason and human skills or upon examination of the design of a sundial or a water-clock to appreciate that calculation of the time of day is made by skill and not by chance, yet none the less to consider that the universe is devoid of purpose and reason, though it embraces those very skills, and the craftsmen who wield them, and all else beside.

This was precisely the line of reasoning adopted by William Paley almost two millennia later: A contrivance implies a contriver, just as a design implies a designer. An intricate watch, Paley contended, attests to the existence of a watchmaker. Therefore, shouldn’t we conclude the same about something as exquisite as life? After all, “Every indication of contrivance, every manifestation of design, which existed in the watch, exists in the works of nature; with the difference, on the side of nature, of being greater and more, and that in a degree which exceeds all computation.” This fervent pleading for the imperative need for a “designer” (since the only possible but unacceptable alternative was considered to be fortuitousness or chance) convinced many natural philosophers until roughly the beginning of the nineteenth century.

Implicit in the design argument was yet another dogma: Species were believed to be absolutely immutable. The idea of eternal existence had its roots in a long chain of convictions about other entities that were considered enduring and unchanging. In the Aristotelian tradition, for instance, the sphere of the fixed stars was assumed to be totally inviolable. Only in Galileo’s time was this particular notion completely shattered with the discovery of “new” stars (which were actually supernovae—exploding old stars). The impressive advances in physics and chemistry during the seventeenth and eighteenth centuries did point out, however, that some essences were indeed more basic and more permanent than others, and that a few were almost timeless for many practical purposes. For example, it was realized that chemical elements such as oxygen and carbon were constant (at least throughout human history) in their basic properties—the oxygen breathed by Julius Caesar was identical to that exhaled by Isaac Newton. Similarly, the laws of motion and of gravity formulated by Newton applied everywhere, from falling apples to the orbits of planets, and appeared to be positively unchangeable. However, in the absence of any clear guidelines as to how to determine which natural quantities or concepts were genuinely fundamental and which were not (in spite of some valiant efforts by empiricist philosophers such as John Locke, George Berkeley, and David Hume), many of the eighteenth-century naturalists opted to simply adopt the ancient Greek view of ideal, unchanged species.