The so called “Duccio Window” was commissioned in 1288 and when completed placed so high in Siena cathedral that it's detail was out of sight. Legend had it that it was designed by Duccio. Recently, it has been restored and was put on view at a convenient height in the Duccio exhibition of 2003. Now it is at ground level in the Museo del Opera del Duomo in Siena. However it is so well protected by distance that you really need binoculars to see the detail that clearly proclaims it cannot possibly still be attributed to Duccio though that is still its official title. The quality of the drawing is so much in advance of anything that Duccio ever produced.


Duccio was a great master; he was able to convey human feeling with wonderful clarity in spite of his primitive style. The window is in a style that I would have guessed it to have been produced after 1430 because it's grasp of the three dimensional aspect of the subject is so sophisticated. We know that the window was commissioned from a stained glass workshop from northern Europe working in Assisi during the construction of the Basilica of St. Francis. Duccio made a copy of a detail of Christ's head for his own Crucifix of 1305 we can therefore deduce the window was in Siena by that time and at ground level.


The names of both Duccio and Cimabue have been associated with the design of the window though neither were named in the contract. As neither were nearly so advanced in the art of drawing found in the window it is safe to assume that the anonymous glass-painters from northern Europe were in fact responsible for the quality of the drawing. This is an intriguing new notion because normally we credit Florence, in particular Brunelleschi's demonstration of 1401 with the invention of single point perspective. Perspective is usually associated with geometric solids; buildings and the recession of streets etc. whose three dimensional form is described on a plane by interlocking two dimensional shapes. In the window we have a number of examples of heads seen with remarkable geometric accuracy though the structure of a head is far less clear than the structure of a building. Brunelleschi drew over the shapes of the Baptistery as seen in reflection in order to analyze how this miracle of perception could happen. It had happened in Greece and Rome many centuries before his experiment. Indeed, at home in Florence Giotto got within hailing distance of Brunelleschi's perspective, which we now call “scientific perspective” to distinguish it from its antecedents arrived at pragmatically. Perspective of a good readable quality was available to artists in Hellenistic times.


The recurrence of this pragmatic perspective in the glass painting at this early date is easily explained by a process later illustrated by Durer, that of tracing on a sheet of glass held vertically in the picture plane between the subject and the fixed eye-point of the observer. What could be more natural to someone painting on glass to have discovered this technique experimentally and to have seen its benefits. David Hockney believes that an image cast by a concave mirror was responsible for the breakthrough that took place around 1400 in Flanders. This is an entirely reasonable assumption but for the fact that glass painters had got there by other means well before that date. The exquisite drawing of VanEyk, for instance, could well have been learned from glass painters. It is not that tracing helps so much in itself but it is an advance on the conceptual drawing used by Duccio. If done with care as in The Window it gives a salutary lesson in seeing reality, which VanEyk appreciated. The perspective of the heads in the window are well in advance of the thrones because the size of the glass sheets available then could not cover the entire image of a throne.


In a YouTube three part cycle on early Sienese painting - Chapter 1- The "Duccio Window", Chapter 2 - Duccio the Master, and Chapter 3 - La Cripta, I compare the drawing in the window with Duccio's drawing. I find the window much more sophisticated. Duccio is justly renowned for his empathy but his understanding of perspective is primitive. Not just in his architectural detail but in his concept of an eye being fish-shaped or a mouth a Cupid's bow. Yes, both are true from a frontal point of view but it is necessary as a draftsman to distinguish when the fish is no longer visible due to the three dimensional form of the eye. This is always acknowledged by the glass painter but seldom if ever by Duccio. Duccio copied a head of Christ in the window for his Crucifix of c1305; I compare the copy with the original to Duccio's detriment. (These demonstrations are useful lessons in the art of drawing.)


The experts are nervous of finding fault with the masters. I have no such inhibitions, by acknowledging the short-comings of masters one establishes their true artistic character. Anything else is incomplete and in the case of Rembrandt has led to many modern misunderstandings. The Window is still attributed to Duccio and this is a roadblock to a better assessment of it's considerable importance historically. Duccio has also been wrongly credited with Martini's advanced perspective view of The Surrender of Archidosso to Guido Riccio; which is quite impossible.


What Brunelleschi achieved was a theoretical basis for a perspective that was marginally superior to that which had already been achieved by pragmatic means; by observation of the two dimensional shapes. One of the values of my comparison of the original with Duccio's conceptual approach is that it demonstrates the dangers of concepts and how careful observation some times aided mechanically has deepened our understanding of the world we inhabit. Though Duccio clearly perceived he could profit from the lessons of the glass painter it was another century before artists completely understood them. Such is the power of the conceptual mode of thought to mask perceived reality. The history of art should concern itself more with this continuing human handicap. Art's chief claim to importance is that it has consistently overcome this wired-in handicap.