The theory
and practice of vision in Leonardo and his followers
Coordinator: Prof. Carlo Pedretti
WEDNESDAY,
MAY 30 2001
"Corpo
nato della prospettiva di Leonardo Vinci, discepolo della sperienza.
Sia fatto questo corpo sanza esemplo d'alcuno corpo ma solamente con
semplici linee"
(Body born of the perspective of Leonardo da Vinci, disciple of experience.
Let this body be made without relation to any body, but out of simple
lines only).
A revealing pentimento shows that Leonardo was about to write
"of any solid body", that is, geometrical body, and in fact
the drawing recalls the mazzocchi of the earlier perspectivists.
But his intention was to depart from the fifteenth-century tradition
of mazzocchio perspective to investigate the dynamic qualities
of a continuous line in space, a concept that will be visually underlined
in much later treatises on perspective, e.g. in Barbaro's of 1569 and
in Sirigatti's of 1596. The same principle of perspective was to be
fully exploited in his later drawings of water currents, as well as
in his anatomical representations of 1505-1510, drawn from a model in
which muscles are reduced to wires to indicate their lines of force.
The dynamic quality inherent in a spiral or coiling form is reflected
even in his drawings of machines for the excavation of canals, which
date from the first years of the sixteenth century.
The
group meets to look first at the Codex Atlanticus sheet of c. 1490 on
which Leonardo draws a serpent-like object in perspective with the note
to it quoted above. It is a sheet full of sketches and diagrams of perspective,
including a puzzling view of the terrestrial globe - a sheet dense of
questions yet to be asked, a document of Leonardo's indebtedness to
tradition - Optics and Cartography - and a symbol of his innovative
views on scientific investigation. The time is that of his Proems
in praise of Nature and Experience, the science for him so seldom
reborn (Galluzzi). This abstract body in perspective - its shape and
meaning to be fully explained during the meeting - is suitable for computer-graphic
animation and could well be translated into a tridimensional model just
like the models of Luca Pacioli's Divina proportione. It would
be a most appropriate, meaningful symbol of the whole workshop.
And there is more to it. Every line of this body betrays its origin
from a point that moves in space to generate it (late in life Leonardo
defines the perspective of the horizon line in the same way), and therefore
to represent form as volume, thus making visible in the viewer's mind
even that which cannot be seen - the back of the object. It is Leonardo's
answer to Parrasio's challenge in antiquity as related by Pliny and
as mentioned in passing by Alberti. This may have something to do with
a lost manuscript page by Leonardo described by Delacroix in 1849.
Alberti, of course, is Leonardo's initial instigator. Paris Ms. A, containing
the bulk of Leonardo's earliest notes for his Book on Painting,
c. 1490-1492, also contains a full commentary on Alberti's so-called
"costruzione legittima" of artificial perspective.
This is something well known but still little understood, particularly
in view of a conflict that was soon to arise from Leonardo's need to
take into account Optics in the traditional sense, possibly through
a first exposure to Ghiberti's Commentari, though there is now
evidence of an even earlier exposure to the mathematical principles
of Euclid's Optics and even of Ptolemy's Cosmology (Sinisgalli).
And Leonardo himself, in Ms. A, refers to his own book on perspective
as a treatise already compiled. Again at an early date Leonardo illustrates
the use of the "bacolo di Euclide" that Gerson and others
were later to apply to astronomical observation. (It may become necessary
to consider the astrolabe in relation to perspective and surveying for
cartography, to explain, for instance, Leonardo's reference to Sirigatti
and his "orologio anello". This may also lead into a discussion
of the most complex problem of sundials, etc.)
The
introductory session to the Leonardo workshop should place an emphasis
on Leonardo's experimentation through models. The first day is an introduction,
or rather a fully discussed survey of the highlights of Leonardo perspective
studies in chronological sequence, through the 1490s and up to 1518.
|