We don’t usually think of Galileo as a geologist or paleontologist, but his catholic (with a small c!) interests encompassed everything that we would now call science, including all of natural history. Galileo took his new telescope to his first meeting of 1611 with Cesi and the Lynxes, and the members all became enthralled with Galileo’s reconstructed cosmos. But he also brought, to the same meeting, a curious stone recently discovered by some alchemists in Bologna, called the lapis Bononensis (the Bologna stone), or the “solar sponge”—for the rock seemed to absorb, and then reflect, the sun’s light. The specimens have been lost, and we still cannot be certain about the composition or the nature of Galileo’s stone (found in the earth or artificially made). But we do know that the Lynxes became entranced by this geological wonder. Cesi, committed to a long stay at his estate in Acquasparta, begged Galileo for some specimens, which arrived in the spring of 1613. Cesi then wrote to Galileo: “I thank you in every way, for truly this is most precious, and soon I will enjoy the spectacle that, until now, absence from Rome has not permitted me” (I read this quotation and information about the Bologna stone in Paula Findlen’s excellent book, Processing Nature, University of California Press, 1994).
A comparison of title pages for Galileo’s book on sunspots and Stelluti’s treatise on fossil wood, with both authors identified as members of the Lynx society.
Galileo then took a reciprocal interest in Cesi’s own geological discovery—the fossil wood of Acquasparta; so Stelluti’s letters reflect a clearly shared interest. Cesi did not live to publish his controversial theories on this fossil wood. Therefore, the ever-loyal Stelluti gathered the material together, wrote his own supporting text, engraved thirteen lovely plates, and published his most influential work (with the possible exception of those earlier bees) in 1637: Trattato del legno fossile minerale nuovamente scoperto, nel quale brevemente si accenna la varia e mutabil natura di detto legno, rappresentatovi con alcune figure, che mostrano il luogo dove nasce, la diversita dell’onde, che in esso si vedono, e le sue cosi varie, e maravigliose forme—a tide almost as long as the following text (Treatise on newly discovered fossil mineralized wood, in which we point out the variable and mutable nature of this wood, as represented by several figures, which show the place where it originates, the diversity of waves [growth lines] that we see in it, and its highly varied and marvelous forms).
The title page illustrates several links with Galileo. Note the similar design and same publisher (Mascardi in Rome) for the two works. Both feature the official emblem of the Lynxes—the standard picture of the animal (copied from Gesner’s 1551 compendium), surrounded by a laurel wreath and topped by the crown of Cesi’s noble family. Both authors announce their affiliation by their name—the volume on sunspots by Galileo Galilei Linceo, the treatise on fossil wood by Francesco Stelluti Accad. Linceo. The ghosts of Galileo’s tragedy also haunt Stelluti’s title page, for the work bears a date of 1637 (lower right in Roman numerals), when Galileo lived in confinement at Arcetri, secretly writing his own last book. Moreover, Stelluti dedicates his treatise quite obsequiously “to the most eminent and most revered Signor Cardinal Francesco Barberini” (in type larger than the font used for Stelluti’s own name), the nephew of the pope who had condemned Galileo, and the man who had refused Stelluti’s invitation to lead (and save) the Lynxes after Cesi’s death.
But the greatest and deepest similarity between Galileo’s book on sunspots and Stelluti’s treatise on fossil wood far transcends any visual likenesses, and resides instead in the nature of a conclusion, and a basic style of rhetoric and scientific procedure. Galileo presented his major discussion of Saturn in his book on sunspots (as quoted earlier in this essay)—where he stated baldly that an entirely false interpretation must be correct because he had observed the phenomenon with his own eyes. Stelluti’s treatise on fossil wood presents a completely false (actually backward) interpretation of Cesi’s discovery, and then uses exactly the same tactic of arguing for the necessary truth of his view because he had personally observed the phenomena he described!
Despite some practical inconveniences imposed by ruling powers committed neither to democracy nor to pluralism—one might, after all, end up burned like Bruno, or merely arrested, tried, convicted, and restricted like Galileo—the first half of the seventeenth century must rank as an apex of excitement for scientists. The most fundamental questions about the structure, meaning, and causes of natural phenomena all opened up anew, with no clear answers apparent, and the most radically different alternatives plausibly advocated by major intellects. By inventing a simple device for closer viewing, Galileo fractured the old conception of nature’s grandest scale. Meanwhile, on earth, other scientists raised equally deep and disturbing questions about the very nature of matter and the basic modes of change and causality.
The nascent science of paleontology played a major role in this reconstruction of reality—primarily by providing crucial data to resolve the two debates that convulsed (and virtually defined) the profession in Stelluti and Galileo’s time (see chapter 1 for more details on this subject):
1. What do fossils represent? Are they invariably the remains of organisms that lived in former times and became entombed in rocks, or can they be generated inorganically as products of formative forces within the mineral kingdom? (If such regular forms as crystals, and such complex shapes as stalactites, can arise inorganically, why should we deny that other petrified bodies, strongly resembling animals and plants, might also originate as products of the mineral kingdom?)
2. How shall we arrange and classify natural objects? Is nature built as a single continuum of complexity and vitality, a chain of being rising without a gap from dead and formless muds and clays to the pinnacle of humanity, perhaps even to God himself? Or can natural objects be placed into sharply separated, and immutably established, realms, each defined by such different principles of structure that no transitional forms between realms could even be imagined? Or in more concrete terms: does the old tripartite division of mineral, vegetable, and animal represent three loosely defined domains within a single continuum (with transitional forms between each pair), or a set of three utterly disparate modes, each serving as a distinct principle of organization for a unique category of natural objects?
Cesi had always argued, with force and eloquence, that the study of small objects on earth could yield as much reform and insight as Galileo’s survey of the heavens. The microscope, in other words, would be as valuable as the telescope. Cesi wrote:
If we do not know, collect, and master the smallest things, how will we ever succeed in grasping the large things, not to mention the biggest of all? We must invest our greatest zeal and diligence in the treatment and observation of the smallest objects. The largest of fires begins with a small spark; rivers are born from the tiniest drops, and grains of sand can build a great hill.
Therefore, when Cesi found a puzzling deposit of petrified wood near his estate, he used these small and humble fossils to address the two great questions outlined above—and he devised the wrong answer for each! Cesi argued that his fossil wood had arisen by transformation of earths and clays into forms resembling plants. His “wood” had therefore been generated from the mineral kingdom, proving that fossils could form inorganically. Cesi then claimed that his fossils stood midway between the mineral and vegetable kingdoms, providing a smooth bridge along a pure continuum. Nature must therefore be constructed as a chain of being. (Cesi had strongly advocated this position for a long time, so he can scarcely be regarded as a dispassionate or disinterested observer of fossils. His botanical classification, eventually published by Stelluti in 1651, arranged plants in a rising series from those he interpreted as most like minerals to forms that he viewed as most like animals.) Since Cesi could not classify his fossils into any conventional kingdom, he awarded them a separate name for a novel realm between minerals and plants—the Metallophytes.
Stelluti, playing his usual game of follow the leader, devo
ted his 1637 treatise to supporting Cesi’s arguments for the transitional status of metallophytes and their origin from the mineral kingdom as transmuted earths and clays. The fossils may look like plants, but they originate from heated earths of the surrounding countryside (where subterranean magmas boil the local waters, thus abetting the conversion of loose earth to solid metallophyte). Stelluti concludes:
The generation of this wood does not proceed from the seed or root of any plant, but only from a kind of earth, very much like clay, which little by little becomes transmuted to wood. Nature operates in such a manner until all this earth is converted into that kind of wood. And I believe that this occurs with the aid of heat from subterranean fires, which are found in this region.
To support this conclusion, Stelluti presented the following five basic arguments:
1. The fossil wood, generated from earth, only assumes the forms of tree trunks, never any other parts of true plants:
It is clear that this wood is not born from seeds, roots or branches, like other plants, because we never find pieces of this wood with roots, or branches, or nerves [internal channels for fluids], as in other [truly vegetable] wood and trees, but only simple trunks of varied form.
Three figures of fossil wood from Stelluti’s treatise of 1637.
2. The fossil trunks are not rounded, as in true trees, but rather compressed to oval shapes, because they grow in situ from earths flattened by the weight of overlying sediments (see the accompanying reproduction of Stelluti’s figure):
I believe that they adopt this oval shape because they must form under a great mass of earth, and cannot grow against the overlying weight to achieve the circular, or rather cylindrical, form assumed by the trunks of true trees. Thus, I can securely affirm that the original material of this wood must have been earth of a clayey composition.
3. Five of Stelluti’s plates present detailed drawings of growth lines in the fossil wood (probably done, in part, with the aid of a microscope). Stelluti’s argument for these inner details of structure follows his claim for the outward form of entire specimens: the growth lines form wandering patterns reflecting irregular pathways of generation from earth, following limits imposed by the weight of overlying sediments. These lines never form in regular concentric circles, as in true trees. Stelluti therefore calls them onde, or “waves,” rather than growth lines:
The waves and veins are not continuous, all following the same form, as in [vegetable] wood, but are shaped in a variety of ways—some long and straight, others constricted, others thick, others contorted, others meandering…. This mineral wood takes its shape from the press of the surrounding earth, and thus it has waves of such varied form.
4. In the argument that he regarded as most decisive, Stelluti held that many specimens can be found 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, or may 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 because he has seen the phenomenon, often several times over many years, with his own eyes.
Stelluti had used this Galilean rhetoric to great advantage before. At the very bottom of his beautiful 1625 engraving of three bees for Pope Urban, Stelluti had added a little Latin note, just under his greatest enlargement of paired bee legs. In a phrase almost identical in form with Galileo’s anagram about Saturn, Stelluti wrote: Franciscus Stellutus Lynceus Fabris Microscopio Observavit—“the Lynx Francesco Stelluti from [the town of] Fabriano observed [these objects] with a microscope.” This time, at least, Stelluti had a leg up on Galileo—for the slow stepper among the Lynxes had made accurate observations, properly interpreted, while Galileo had failed for the much more difficult problem of Saturn. (This note, by the way, may represent the first appearance of the word microscope in print. Galileo had called his instrument an occhiolino, or “little eye,” and his fellow Lynxes had then suggested the modern name.)
But Stelluti’s luck had run out with Cesi’s wood, when the same claim now buttressed his errors. Consider a sampling, following the order of his text, of Stelluti’s appeals to the incontrovertible status of direct observation:
The generation of this wood, which I have been able to see and observe so many times, does not proceed from seeds…
The material of this wood is nothing other than earth, because I have seen pieces of it [perche n’ho veduto io pezzi] with one part made of hard earth and the other of wood.
Figure 7 shows a drawing of a large oval specimen, which I excavated myself from
the earth.
The outer surface of the other piece appears to be entirely in wood, as is evident to the eye [in the drawing presented by Stelluti].
Stelluti ends his treatise with a flourish in the same mode: he need not write at great length to justify his arguments (and his text only runs to twelve pages), because he has based his work on personal observation:
And this is all I need to say, with maximal brevity, about this material, which I have been able to see and observe so many times in those places where this new, rare, and marvelous phenomenon of nature originates.
But Stelluti had forgotten the old principle now embodied in a genre of jokes that begin by proclaiming: “I’ve got some good news, and some bad news.” Galileo’s empirical method can work wonders. But hardly any faith can be more misleading than an unquestioned personal conviction that the apparent testimony of one’s own eyes must provide a purely objective account, scarcely requiring any validation beyond the claim itself. Utterly unbiased observation must rank as a primary myth and shibboleth of science, for we can only see what fits into our mental space, and all description includes interpretation as well as sensory reporting. Moreover, our mental spaces house a complex architecture built of social constraint, historical circumstance, and psychological hope—as well as nature’s factuality, seen through a glass darkly.