I thought a little further (from yesterday’s post) about van Eyck and settled in on his painting of the newly married (The Arnolfini Marriage, painted in 1434, depicting the union of Giovanni Arnolfini and Giovanna Cenami, who married in Bruges in that year), and the very unusual image of the scene as reflected in the convex mirror directly behind the couple. It is a wonderful painting of course, lusciously and richly colored--the observer, though, is brought instantly to the mirror. And in that reflection is what is seen from behind the couple as well as what the couple is seeing--in a sense, a 180-degree view of the room (if we considered the painter's perspective towards the couple as 90-degrees). It is one of the first times that a mirror is used in this fashion and is also offers a great instruction on the newly-rediscovered perspective. (The inscription above the mirror, which is surrounded by ten scenes from the life of Christ, reads “Jan van Eyck was present"--and probably was literal, as we see the painter himself reflected in a tiny portrait...along with another man, who may also have been involved with the wedding).
As a matter of fact, it is just 30 years earlier that Filippo di Ser Brunellesci (1377-1446) used mirrors as a tool in "creating" the first paintings in linear perspective in modern times--and he uses the mirrors in such a way as to compare what he was seeing in front of him, rather than using them to gain a sight-line for things that he couldn't see. But they did in a way do just that. Brunellesci set his position inside the unfinished Santa Maria del Fiore (Florence), and used the apparatus (pictured here from the linked website) to record the facade of San Giovanni de Firenze (better known by its subsequent name, the Florentine Baptitstry, as all Florentine Catholics were Baptized there well into the 19th century) which was opposite his position across the Piazza del Duomo. He effort was a panel which was finished between 1407 and 1410, and which is now lost to time and space.
It should be noted that the Baptistry, an 8-sided figure (with another, triangular, form added later; and 8-sided to represent the octava dies, the "eighth day," the day of the risen Christ, which would be outside the scope of time and measurement) was decorated with colossal, fantastically beautiful doors, some of which were created by none other than Ghiberti, another (slightly later) master of linear perspective.
(The image below is taken from the very useful site which goes into
good detail about the Brunellesci pin/peephole experiment)