Free Hen’s Teeth and Horse’s Toes by Stephen Jay Gould Page A

the five visible planets of an older cosmology) and seven notes in a musical scale, why not imbue rocks with the plastic power to form objects precisely like the parts of animals? After all, the glossipetrae came from rocks and rocks were created as we find them. If the tongue stones are sharks’ teeth, how did they get inside rocks? Moreover, the earth is only a few thousand years old, and tongue stones inundated European collections. How many sharks could have infested Mediterranean waters in so short a time?

    A mid-eighteenth century illustration of why glossipetrae (A, B, and C) must come from the mouths of sharks. FROM DE CORPORIBUS MARINIS LAPIDESCENTIBUS (ON PETRIFIED MARINE BODIES) BY THE SICILIAN ARTIST-SCIENTIST AUGUSTINO SCILLA .
    Steno observed that his shark had hundreds of teeth and that new ones formed continually as old teeth wore down and fell out. The numbers of glossipetrae from Malta no longer foreclosed an origin in sharks’ mouths, even under the Mosaic chronology (which Steno did not question). According to the common legend that great scientists are unprejudiced observers who can shuck constraints of culture and see nature directly, Steno came to his correct conclusion—that glossipetrae are fossil sharks’ teeth—because he made better observations. Steno was a fine observer, but he was also an adherent to the new mechanical philosophy that insisted on physical causes for phenomena and viewed detailed internal similarity as a sure sign of common manufacture in the mechanical sense. Steno did not see better; rather, he possessed the conceptual tools to interpret his excellent observations in a necessary way that we continue to regard as true.
    But Steno then abstracted the problem of glossipetrae in a remarkably original manner—and achieved with this great insight his role as the founder of modern geology. The tongue stones found within rocks, Steno reasoned, were problematic because they were solids enclosed within a solid body. How did they get in there? Steno then recognized that all the troubling objects of geology were solids within solids—fossils in strata, crystals in rocks, even strata themselves in basins of deposition. A general theory for the origin of solids within solids could provide a guide for understanding the earth’s history.
    Taxonomy is often regarded as the dullest of subjects, fit only for mindless ordering and sometimes denigrated within science as mere “stamp collecting” (a designation that this former philatelist deeply resents). If systems of classification were neutral hat racks for hanging the facts of the world, this disdain might be justified. But classifications both reflect and direct our thinking. The way we order represents the way we think. Historical changes in classification are the fossilized indicators of conceptual revolutions.
    The French scholar Michel Foucault uses this principle as his key for understanding the history of thought. In Madness and Civilization , for example, he notes that a new method of dealing with the insane arose in the mid-seventeenth century and spread rapidly throughout Europe. Previously, madmen had been exiled or tolerated and allowed to wander about. In the mid-seventeenth century, they were confined in institutions along with the indigent and unemployed, a motley assemblage by modern standards. We might regard this classification as senseless or cruel, but as Foucault argues, such a judgment will not help us to understand the seventeenth century.
    Why classify together the poor, the unemployed, and the insane; what common theme could inspire such an ordering? Foucault argues that the birth of modern commercial society led to a new designation of the cardinal sin, the one that had to be made invisible by confining all those who, for whatever reason, wallowed in it. That sin was idleness, and Foucault shows that sloth replaced the old medieval curse of pride as the most fundamental of the seven deadly sins in