Ghent Proceedings


‘Optics, Instruments and Painting, 1420–1720: Reflections on the Hockney-Falco Thesis,’ special issue of Early Sciences and Medicine, Vol. X, No. 2 (Brill Academic Publishers, 2005), Sven DuprĂ©, editor (Christoph LĂŒthy, journal editor).

This volume resulted from a 2003 workshop with 25 attendees, most of whom were historians. Although there were 25 speakers, only eight people were asked to write papers for this volume. Six of those were historians of science (one of whom did not attend the workshop, and thus did not hear any of the 25 talks), and one each is by an art historian and an architect. One of the organizers, Sven DuprĂ©, contributed an article of his own, as well as wrote the overall Introduction to this volume. Although DuprĂ© accepts our claims for the post-1550 period (i.e. after the earliest currently-known textural description of a projection), for the pre-1550 period he concludes that “The material evidence [provided by Sara Schechner] flatly contradicts the Hockney-Falco thesis, and while the textural evidence on its own cannot fully exclude the discovery of image projections, taken together with [Schechner’s] material evidence of poor quality mirrors, the painterly use of image projection becomes extremely unlikely.” Unfortunately, as I show below, DuprĂ©’s faith in the material evidence provided by Sara Schechner—who did not attend the workshop— was misplaced.

Even with the flaw noted above, and although additional historical information has come to light in the years since that conference, these proceedings represent the thoughts of seven historians at that time, so it is worthwhile to see where they stood on the Hockney-Falco thesis for the pre-1550 period. Taking them in order, from positive to negative:

  • Antoni Malet is neutral to slightly positive on the Hockney-Falco thesis, pointing out that “Whether or not artists used instruments to inspire them, it was only a posteriori that Kepler turned artists’ pictures into ideal models of objective visual images.”
  • Mark Smith is neutral, offering an explanation for why there would have been a lack of contemporary textual evidence for the use of optics. Smith writes, “But it was never my intention to demonstrate that Hockney and Falco are right. It was, rather, to demonstrate that they are not necessarily wrong in light of my contention that, if image-projection had been discovered by the early fifteenth century, it is more likely to have been discovered by artists than by Perspectivist opticians. Consequently, if Renaissance artists did make that discovery, they did so in spite of, not because of, what they learned from Perspectivist sources.”
  • Filippo Camerota is neutral, pointing out that the documentary history of the use of optical instruments as perspective devices only begins in the seventeenth century and, as Hockney and I have emphasized from the start, he says that “…looking at paintings as if they were photographs is simply wrong.”
  • Sven DuprĂ© is neutral to somewhat negative in his paper, which is limited to showing that Leonardo da Viinci’s surviving drawings “…cannot be used as evidence for this claim.” (note: this statement does not imply that we have used Leonardo’s drawings as evidence, which we have not). His overall conference summary for the pre-1550 period, which heavily relies on Sara Schechner’s paper, is negative. However, his overall summary for the post-1550 period is positive, writing that “Forcing historians of science to come to grips with the transformation that optics underwent in the sixteenth and seventeenth centuries… [is] research opened up by the Hockney-Falco thesis.”
  • The art historian Yvonne Yiu is negative, also pointing to the lack of written evidence in contemporary texts in concluding “The fact that these texts do not mention the concave mirror projection method described by Hockney and Falco speaks strongly against its use in the early Renaissance.” However, I note that several of the texts she cites are on self-portraiture, where projected images would not have been of use, accounting for the lack of discussion in those texts. Also, her conclusion is limited only to concave mirrors, not to the use of refractive lenses.
  • Sara Schechner definitely is negative, writing that “Inspection of surviving mirrors and related objects shows that they were too crude to offer the early Renaissance painter an optical short-cut to a naturalistic image of his subject. The craftsmanship of mirror makers was independent of and inferior to the quality of theories of image formation of the day.” Further, she writes “Medieval mirrors of metal were also small, dark, and convex
 By the sixteenth century, the so-called ‘steel mirrors’ were non-ferrous and praised for their improved brightness.” However, directly contradicting her understanding, recently we found a detailed description for making large, bright, concave, ferrous, steel mirrors in a manuscript about parabolic mirrors known to date from no later than 1372 (i.e. a half-century before van Eyck). The translation of this manuscript is in a 1980 monograph by a well-known historian of Medieval science at Princeton, who is not referenced by Schechner. Also, Schechner failed to realize that no iron mirror could have survived for over 500 years without very serious degradation (i.e. rust). As the historian Vincent Ilardi writes in his book ‘Renaissance Vision, From Spectacles to Telescopes’ (American Philosophical Society, 2007), “[Schechner’s] reservations cannot be entirely accepted in my view because comparing the clarity of metal mirrors 500 years old and ravaged by time with that of presumably new or fairly new mirrors used by Renaissance artists would not be an accurate comparison
 It is more consonant with the above evidence, therefore, that the mirrors of the age were not perfect but were substantially adequate for artistic practice.”
  • Christoph LĂŒthy definitely is negative: “When applied to the period pre-1600, the strong thesis [of the direct use of optical projections] remains fairly implausible, for a variety of reasons that are discussed notably in the contributions by Camerotta, DuprĂ©, Schechner, Smith, and Yiu to this fascile.” Note, however, that although LĂŒthy points to Smith and Camerotta as supporting his own negative conclusion, their papers actually are neutral. Also, he relies on the incorrect information in Schechner’s paper.
  • The eighth paper in this volume, by Philip Steadman, is limited to the much later use of optics by Vermeer in the 17th century (something that itself is by no means universally accepted by art historians; one of the strong critics of our conclusions, Walter Liedke of the Metropolitan Museum, is also a strong critic of Steadman’s).

Unfortunately, in reaching their conclusions for the pre-1550 period, other historians at this workshop relied heavily on Sara Schechner’s incorrect technical and historical information. In his Introduction DuprĂ© writes “Schechner’s contribution strongly brings out that even if someone might have thought of projecting an image in the fifteenth and sixteenth centuries, contemporary materials conditions would not have allowed for it.” DuprĂ© is incorrect here for two reasons: first, knowledge for making appropriate mirrors was available at the time. Second, our thesis is about the use of optics to project images, not necessarily concave mirrors (although, there is circumstantial evidence for the latter). The spectacles that were being produced in quantity a full century before the time of van Eyck were capable of projecting every feature we have shown to be based on optics.

In summary, the conclusions of this selection of seven historians out of the 25 who spoke at the workshop range from slightly positive, to negative on the Hockney-Falco thesis for the period before 1550, but positive for the period after 1550. If the conclusions of these seven historians are representative of the entire discipline as of 2003, roughly half are neutral and half are negative for thes period prior to the earliest currently-known textural reference to projections. However, historians rely very strongly on textural evidence (more of which has come to light in the years since the workshop was held), whereas our thesis relies largely on the visual evidence we discovered.

New documentary evidence will continue to influence historians on this topic, as seen from what Vincent Ilardi writes in ‘Renaissance Vision, From Spectacles to Telescopes’ (American Philosophical Society, 2007): “This monograph is based on a great number of new archival documents discovered only in the last half dozen years. … In 1549 [Lorenzo Lotto] paid the enormous sum of 22 Venetian lira for a ‘big crystal mirror’ ordered from Venice to replace a broken one while he was working in Acona. … In sum, these few entries in Lotto’s account book and the evidence presented above demonstrate that mirrors were used by most or many artists to project images and/or control the accuracy of their visual observations.”


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