Artwatch UK

Fake or Fortune: Hypotheses, Claims and Immutable Facts

We have received two communications on “La Bella Principessa”, which drawing some take to be by Leonardo da Vinci. One came from the work’s owner, the other from a disinterested scholar in confirmation that the work could not, for reasons of arithmetic and plain physical facts, have been made by Leonardo for inclusion in a book.


Above, Fig. 1: The full vellum sheet of the proposed Leonardo drawing “La Bella Principessa”.


This drawing was presented anonymously to the world in 1998 without authorial ascription and without an atom of provenance. When claims of autograph Leonardo authorship were made after barely a decade, it became necessary to fill a five-hundred years long void of records in order to dispel suspicions of forgery or pastiche. In 2010 Professor Martin Kemp bundled together what he held to be a “barrage of evidence – stylistic, historical or technical” that somehow provided collectively what no individual parts constituted: proof that Leonardo da Vinci was the author of what he (Kemp) dubbed “La Bella Principessa”. Thus, a collection of not-evidence was vested with quasi-evidential force on a circular, question-begging appeal to the claimed authority of a “sustained, collective sense that the portrait ‘belongs’ to Leonardo and contributes something new to the Leonardo we currently know.”

Although some scholars (chiefly Italian) were persuaded by the claims, for the consensual majority who did not see Leonardo’s hand in the drawing, Kemp’s methodological ju-ju gained no traction. His claims were advanced in a portmanteau book of collective advocacy, La Bella Principessa – The Story of the New Masterpiece by Leonardo da Vinci, which he co-wrote with Pascal Cotte of Lumiere Technology (the firm hired by the drawing’s owner, Peter Silverman, to conduct technical research) and which carried highly supportive contributions by Peter Paul Biro, Eva Schwan, Claudio Strinati and Nicholas Turner; London, 2010 (– see pp. 187-88).


During Pascal Cotte’s technical analysis of the drawing it was noticed that three holes are present on the left-hand edge. Cotte took these to “prove that it originally came from a book or a manuscript” (- Kemp/Cotte 2010, p. 113). Working with Mr Cotte, Prof. Kemp proposed that the hypothetical book might well have been a collection of celebratory poems of Bianca Sforza who had died in childhood and that “La Bella Principessa” had been made as an illustration to such a book.

Above, Fig. 2: “La Bella Principessa” with Pascal Cotte’s indicated locations of the three supposed stitch holes.

Kemp’s elaborate hypothetical advocacy constituted a daisy-chain of improbabilities. This is a drawing made in the manner of a distinctive (and invariably painted) profile portrait type that is nowhere encountered in recorded Leonardos – and, indeed, this is the very type which Leonardo famously subverted with his own revolutionary plastically dynamic figural innovations. Within the rigorous constraints of the strict profile type, this drawing’s supposedly high-born subject is bereft of the customary/requisite opulence in clothing and jewellery. The eccentric iconography was made on an atypical support – vellum. It was drawn, Kemp holds, either directly from the subject in celebration of her wedding, or, as a commemorative portrayal after her death and thus made either in recollection or from some other depiction. No explanation was offered for how this single image might have resulted from two radically different circumstances of execution.


On a suggestion from Professor David Wright, Kemp proposed that this from-life or post-death portrait had been made to be incorporated within a large, heavy book of the mid-1490s that is now housed in Poland, the so-called Warsaw Sforziad. In the wake of a great deal of (Kemp and Silverman-activated) archival research which found no mention of any work resembling “La Bella Principessa”, it can be seen that without this claimed Warsaw connection, the drawing would remain what it was on its 1998 debut: a stylistically untypical and unprecedented work without any history – the inclusion of which within Leonardo’s oeuvre would, in Prof. Kemp’s own advocacy, “contribute something new to the Leonardo we currently know” and “reveal a previously unknown dimension to the way in which he fulfilled his duties at the court of Duke Ludovico Sforza”. (Kemp/Cotte, 2010, p. 188.) Without history, that is to say, other than the time it is now said to have been in the possession of the restorer/painter Giannino Marchig, the late husband of the anonymous vendor in 1998.

It has been claimed many times that a ‘match’ exists between the drawing’s holes and the book’s stitches but, aside from the small format photo-diagram at Fig. 3, this has never been demonstrated or independently corroborated. Similarly, it has been said that carbon dating tests established that the vellum sheet on which the drawing was made is of an age securely consistent with a drawing being made by Leonardo in the mid-1490s. This claim is seriously misleading, as is shown below.


Before Prof. Wright’s suggestion, in 2010 Pascal Cotte regarded the three holes on the drawing’s left-hand edge as evidence that might identify incorporation within a specific book:

“It would be interesting to use the evidence of the nature and placement of these needle holes to look for other surviving quires from the same codex, which, with other physical clues, might shed further light on the provenance and original commission.”

(Kemp/Cotte, 2010, page 113.)

Cotte’s hope was reasonable but such testimony can cut both ways. Establishing a relationship between the drawing and a particular book requires an exact correspondence between the drawing’s holes and a book’s stitches. Two separate claims were made of a discovered fit with the Warsaw Sforziad, first by the drawing’s owner, Peter Silverman, and then jointly by Martin Kemp and Pascal Cotte. Both occasions were filmed by National Geographic but only the second was broadcast. In it, Kemp expressed himself as being 80% confident. The presently claimed location of the drawing is at the front of the Sforziad. Clearly, the credibility of what is now a 200 million euro-insured drawing that is stored in the Geneva Free Port depends greatly on confidence being maintained in this claimed connection.

Above, Fig. 3: A facsimile of “La Bella Principessa” inserted into the Warsaw Sforziad with five arrows marking the
book’s stitches and three circles in which matches are claimed, but are not evident, between the drawing’s holes and
the book’s outer and central stitches. (The stitch marked by the right-hand arrow is shown in close-up below at Fig. 5.)

As previously shown, our colleague in ArtWatch, Dr Kasia Pisarek, has catalogued very many discrepancies between the drawing and the book, the most problematic being that the former has only three stitch holes, when the latter was bound with five stitches. To cope with this material/arithmetical incompatibility, Kemp and Cotte conjured two hypotheses.

The first was that the book had originally been bound with only three stitches and that at some undated point the drawing had been removed during a rebinding in which two extra stitches were added to the book. That (unsupported) contention was technically implausible: the book is too large and heavy to be supported by just three stitches – and
both of its sister volumes in London and Paris were bound with five stitches.

The second, and now preferred, hypothesis is that the book was indeed originally bound with five stitches and that, as
a part of this book, the drawing originally possessed the requisite five stitch holes, two of which had subsequently been cut off from the sheet. We demonstrated the impossibility of that claim in an earlier post. (To recap briefly: as Cotte had acknowledged in 2010, stitch holes are always made in a straight line along the crease in a group of folded sheets. Given that a central and two outer stitch holes are all present on the “La Bella Principessa” sheet, any original intermediary stitch holes would necessarily be found in alignment with the present three holes on the sheet as it is today.)

In addition to the absence of the two requisite stitch holes, the sheet itself is a mismatch in terms of colour, texture and size with the sheets in the book. Kasia Pisarek now adds a further mismatch:

“The follicles in the ‘La Bella Principessa’ vellum are tightly spaced, while those in the Sforziad vellum are widely spaced. This can be seen on the Polona website, where you can zoom in until you can see the follicles as dots. I remember seeing some pages where the dots were more apparent and they were definitely widely spaced.”


Yet another unaddressed difficulty concerns the back of the drawing. One of the earliest proponents of a Leonardo ascription, Dr Cristina Geddo, has described the presence on the reverse of the drawing of random lettering and an image of a dragon. Kemp and Cotte seem not to have offered an explanation for this content (which, presumably, was revealed by Cotte’s penetrative photography) even though they now claim that the back of the drawing would have faced the book’s beautiful and elaborately painted, symbolically-charged frontispiece. What conceivable iconographic function might such a melange have served in that strategic context of so important and precious a book? Dr Geddo has called for the vellum drawing to be removed from its (most unusual) oak panel support but the owner has declined to do so on grounds of safety. Some of the lettering is visible in an X-ray photograph published in the 2010 and 2012 English and Italian editions of the Kemp/Cotte joint book.


As we reported previously, with regard to the Three Holes v. Five Stitches conundrum, the problems for supporters of “La Bella Principessa” have now become insurmountable: Pisarek established on her second examination of the Warsaw Sforziad in the Polish National Library that while the drawing bears only three holes, the book itself was not only bound with five stitches but that each of those stitches passed through two holes that were two or three millimetres apart (see Figs. 6, 7 and 8 below). At a stroke, the previously claimed ‘fit’ between the drawing and the book is demolished: the drawing possesses only three single stitch holes when it should have five pairs of holes making ten in total. Even if it were to be conceded that two inner stitches might once have been present, today’s three single holes should be three pairs of holes, making six holes in total, not three.


When we sent our previous “La Bella Principessa” post with the newly disqualifying physical/technical evidence to the drawing’s owner, Peter Silverman, (13 June), he dismissed the bearers of the information by alleging lack of expertise: “I leave the attribution question to serious and highly qualified experts!!!” In support of his professional slur, Silverman copied-in two messages to us. The first had been sent to him, at his request, by a costume expert, Elisabetta Gnigera. The second Silverman had sent to Jean Penicaut, the CEO of Lumiere Technology. It was evidently written in haste and heat:

“Dear Jean
I am sorry but we, as owners of the BP, are not to be told how and with whom to talk! I understand your frustration in dealing with Artwatch and Franck but i feel that Pisareks statement must not and cannot be left unchallenged! I therefore request you to rebut each and every point in this latest statement-most importantly of all i would like to see the INDISPUTABLE proof of the binding holes, in a first and separate email to me! Unfortunaley Martin has made statements which can be perverted by anyone in bad faith-equivocal statements quoted in the first part of the enclosed article!!
“I would like Elisabetta to comment on the costume questions.
And i would like YOU to extensively quote from the lab results of La Veneria*, which is very helpful to our cause! [*This is a reference the conservation laboratory “La Venaria Reale” which has conducted analysis of the drawing.]
“We cannot afford to lose the high ground’ in this battle-no matter the bad faith of our ennemy.
“To avoid your corresponding with them please send the rebuttal to me. I INSIST THAT THIS IS AN ABSOLUTE NECESSITY!!
Best, peter

“PS-the good news is that there is a very serious party interested in acquiring a share in the BP(highly confidential) and July 1 will be a decisive day!!!”

It would seem after more than a month that Lumiere Technology has not provided the owner with indisputable evidence of a connection between the drawing and the Warsaw book that would counter Pisarek’s account. On 14 June we replied to Mr Silverman:

“Speaking of clarification and your requests, I note the various requests from the ‘owners of the BP’ to your associates
to read our current post, and your talk of a prospective part-sale of the BP. Can I take it that the potential buyer of whom you speak has been similarly advised?

“Also, perhaps you might say how you will respond if Jean Penicaut advises you, as we would predict, that he can find
no ‘INDISPUTABLE proof of the binding holes’ that might enable you – or he on your behalf – ‘to rebut each and every point in this latest statement [in the then current AWUK post]’”?

Concerning the La Venaria Reale laboratory reports, we asked Mr Silverman on 15 June:

“On your technical ‘proofs-of-authenticity’ and our possible viewing of your Swiss-vaulted, soon-to-be part-sold drawing, might we not deal with both by: a) your sending to us all reports and data that have been made available to you; and, b) your bringing the drawing to either Paris or London so that we might arrange a group viewing by sceptics and rejecters?”


After more than a month we have received no technical reports on “La Bella Principessa”. Lumiere Technology’s
apparent silence on the conflicting number of stitch holes seems remiss. In our experience it is valuable to see the reports themselves because evidence can sometimes be interpreted and presented in ways that might mislead. For example, it has been claimed (technically-speaking correctly) that carbon dating has established a 95.4% probability
that “La Bella Principessa” had been made at some point between 1440 and 1650. On that particular technical examination and very wide range of possible ages, Pascal Cotte (2010, p. 110) has claimed a number of things in a single sentence:

“This dating confirms that the portrait could well have been made in Leonardo’s lifetime, supporting Martin Kemp’s proposed date in the mid-1490s and virtually eliminating the possibility that it is a 19th century pastiche.”

This was all quite misleading. A confirmed “could well have” remains a “could have” and does not become a confirming “was”. A “virtually eliminated possibility” remains a possibility. Taken as a whole and properly appraised, the data itself cannot reasonably be said to support Kemp’s claimed date and authorship – in fact, it does the opposite.

Cotte’s claims rest on what is only a loose and very wide overall estimation of probability. While it is true to say there is a 95.4% chance that the sheet appeared at some point between 1440 and 1650, there is not a 95.4% probability that it appeared before the mid-1490s when the Sforziad was made. Even on that loose, overall range of possibilities, it would be more accurate to say that because we know (today) that the Warsaw book was made in the 1490s (and had known in 2010 that the proposed subject of “La Bella Principessa”, Bianca Sforza, had died in 1496), it is three times more likely that the “La Bella Principessa” sheet post-dated rather than predated the book. What has not been acknowledged is that within the overall figure, the probabilities had been greatly more precisely quantified.

It was said in the report, for example, that there was a 68.2% probability that the sheet was made between 1470 and 1650 and that, within this period (see Fig. 4 below), there was only a 27.2% probability that the drawing was made between 1470 and 1530 – and this was compared against the appreciably greater probability (41.0%) that the sheet was made some time between 1550 and 1650 – which would place the sheet altogether much later than Leonardo who died in 1519. Properly read, with a proposed date for the drawing set in the mid-1490s, the data shows that there was only a 13.6% probability that the “La Bella Principessa” sheet existed when the book was made. When the general 95.4% probability of an origin anywhere between 1470 and 1650 and the 13.6% probability of an origin between 1470 and 1495 are expressed as racing odds, it is seven times more likely that the sheet was made after the book than before it. And the odds of seven to one against pertain to the vellum sheet itself, not to the possible dates of execution for the drawing. Even if this sheet had once been present in that book, such a dating would indicate only the age of the material, not the date of the drawing’s execution. On this last, we should recall that Eric Hebborn advised in his The Art Forger’s Handbook that a prime source of old materials for forged drawings is obtained from blank end papers in books. Thieves cut valuable illuminated pages from books. Forgers crave blank pages but will make use of a blank side by gluing its reverse firmly to some impenetrable material.

Above, Fig. 4: The carbon dating report on the “La Bella Principessa” sheet (as published by Kemp/Cotte, 2010, p. 110).


Where Mr Silverman declines to make reports available to us, and Pascal Cotte fails to demonstrate a fit between the drawing’s three stitch holes and the book’s ten stitch holes, we now present further visual proofs and documentary confirmation of the previously claimed mismatch to demonstrate precisely why “La Bella Principessa” could never have been part of the Warsaw Sforziad.


On 23 June 2016 Barbara Dzierzanowska, the Head of Department of Old Prints BN at the National Library of Poland, wrote to Kasia Pisarek:

“Dear Madam,

I would like to inform you that yesterday we entered the Treasury and re-examined the Sforziad, which has confirmed that the binding stitches are double and there are 10 holes.

Yours sincerely,

Barbara Dzierzanowska”


That the stitching of the Sforziad was made through double holes can be seen by eye on the book itself, as shown below at Fig. 5.

Above, Fig. 5: A stitch made through two holes, as seen on the numbered page 1 of the Warsaw Sforziad. In this photograph, the top stitch and the two flanking holes are shown but some of the other holes can also be seen on stitches below it. This stitch/holes configuration would have been evident when (as described above) a full-size facsimile of “La Bella Principessa” was inserted into the Sforziad at precisely this point. This evidence is also available online: our image was taken from the detailed record of the entire book that is carried on this site: Polona – La Sforziada.


When Kasia Pisarek inspected the book for the second time, she asked that the dimensions of the pages and the relative positions of the stitch holes be marked along the edge of a piece of paper. This was done by the library’s books’ conservator in her presence and that of the chief librarian. Intervals between the stitch holes were marked in pencil along the two sides of the strip of paper and these are shown here at Figs. 6 and 7. When we marked off those measurements onto a separate sheet of paper, to prepare the diagram at Fig. 8, and then measured them on our sheet with a ruler, they were all exactly as given by Pisarek. We can be sure, therefore, that the dimensions and ratios between the stitch holes as shown below at Fig. 8 have been accurately established and physically transported to ArtWatch UK – and at practically zero-cost by means of sharp pencils and two pieces of paper.

Above, Figs. 6 (top) and 7: The strip of paper on which the book’s page size and stitch holes were recorded, as described above.

The conservator explained to Pisarek that the present positions of the stitch holes were those of the original construction of the book and that, therefore, there was no possibility that the book had once been bound with only three stitches. She made diagrams on the strip showing (at Fig. 7) different ways of executing stitching with double holes.


1) According to Kemp and Cotte, the dimensions of the vellum pages of the Sforziad vary from 33.0 to 33.4 cm in height, while the drawing is 33 cm high.

2) I have carefully checked the dimensions with the Librarian in March 2016. All the pages are at least 33.4 cm high and more, up to 33.7 cm. The size of 33 cm would be far too small for the book.

3) The 5 holes in the book are in fact all double holes. Each of the 5 holes is two small holes, between which a string passes. The distance between the two small holes is about 3 mm. The double holes were never mentioned by Kemp or Cotte.

4) According to the conservator who was present at the time of my last visit, this is the binding that follows the original binding as there is no damage of any kind. So in total there were as many as 10 small holes, not 3 single ones as in the drawing.

5) I measured the distances between the 3 holes that Kemp and Cotte measured in La Bella Principessa. The measurements were taken from the middle of the double holes.

6) The distance between the bottom hole and the middle hole is 11.35 cm in the Sforziad, while in the drawing it is 11.06 cm.

7) The distance between the middle hole and the top hole is 11.7 cm in the Sforziad, while in the drawing it is 11.44 cm.


Above Fig. 8: We took the dimensions of the Sforziad’s page and stitch holes from the strip of paper marked by the Polish National Library’s books’ conservator (as shown at Figs. 6 and 7) and drew them in black, as above, and marked “WS”. We then drew in red the “La Bella Principessa” sheet (here marked “LBP”) and its stitch holes as given above by Pisarek.
As can be seen above, it is impossible to align the drawing’s single stitch holes with their claimed counterparts in the book. If the drawing’s centre hole is aligned with the centre of the two central holes in the book (as shown on the left here), its other two holes fall short of their claimed counterparts.
If the LBP drawing’s upper hole is aligned with the centre of book’s two upper holes, its central and lower holes fall progressively further short of their claimed counterparts on the book.
In short, there is no fit or match between the book and the drawing – and which drawing in all probability post-dated the book, for reasons indicated above.

Those who would continue to give this drawing to Leonardo must now find some other means of filling a five centuries absence of provenance and of squaring intractable technical circles. We will examine next the supposed left-handed execution of “La Bella Principessa”.

Michael Daley, 21 July 2016

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