Free The Lying Stones of Marrakech by Stephen Jay Gould Page B

in the process of transition, with some parts still made of formless earth, others petrified in the shapes of wood, and still others fully converted to wood. Stelluti views these stages as an actual sequence of transformation. He writes about a large specimen, exposed in situ:
    In a ditch, we discovered a long layer of this wood … rather barrel-shaped, with one segment made of pure earth, another of mixed earth and wood, and another of pure wood…. We may therefore call it earth-wood (creta legno) .
    Later, he draws a smaller specimen (reproduced here from Stelluti’s figure) and states:
    The interior part is made of wood and metal together, but the crust on the outside seems to be made of lateritic substance, that is, of terra cotta, as we find in bricks.
    5. In a closing (and conclusive) flourish for the empirical method, Stelluti reports the results of a supposed experiment done several years before:
    A piece of damp earth was taken from the interior of a specimen of this wood, and placed in a room of the palace of Acquasparta, belonging to Duke Cesi. After several months it was found to be completely converted into wood—as seen, not without astonishment, by the aforementioned Lord, and by others who viewed it. And not a single person doubted that earth was the seed and mother of this wood [ la terra è seme e madre di questo legno ].
    With twentieth-century hindsight, we can easily understand how Stelluti fell into error and read his story backward. His specimens are ordinary fossil wood, the remains of ancient plants. The actual sequence of transformation runs from real wood, to replacement of wood by percolating minerals (petrifaction), to earth that may either represent weathered and degraded petrified wood, ormay just be deposited around or inside the wood by flowing waters. In other words, Stelluti ran the sequence backward in his crucial fourth argument—from formless earth to metallophytes located somewhere between the mineral and vegetable kingdoms!
    Moreover, Stelluti’s criteria of shaping by overlying sediments (arguments 2 and 3) hold just as well for original wood later distorted and compressed, as for his reversed sequence of metallophytes actively growing within restricted spaces. Delicate parts fossilize only rarely, so the absence of leaves and stems, and the restriction of specimens to trunks, only records the usual pathways of preservation for ancient plants, not Stelluti’s naive idea (argument 1) that the tree trunks cannot belong to the vegetable kingdom unless fossilized seeds or roots can also be found. As for the supposedly crucial experiment (argument 5)—well, what can we do with an undocumented three-hundred-year-old verbal report ranking only as hearsay even for Stelluti himself!
    Nonetheless, Stelluti’s treatise played an important role on the wrong side of the great debate about the nature of fossils—a major issue throughout seventeenth-century science, and not fully resolved until the mid-eighteenth century (see essay 1, about a late defense from 1726). Important authors throughout Europe, from Robert Plot in England (1677), to Olaus Worm in Denmark (1655), reported Stelluti’s data as important support for the view that fossils can originate within the mineral kingdom and need not represent the remains of organisms. (Stelluti, by the way, did not confine his arguments to the wood of Acquasparta but made a general extrapolation to the nature and status of all fossils. In a closing argument, depicted on a fateful thirteenth plate of ammonites, Stelluti held that all fossils belong to the mineral kingdom and grow within rocks.)
    When we evaluate the logic and rhetoric of Stelluti’s arguments, one consistent strategy stands out. Stelluti had finally become a true disciple of Galileo and the primacy of direct empirical observation, viewed as inherently objective. Over and over again, Stelluti states that we must accept his conclusions