Interior and Dome
In constructing the San Lorenzo, and thirty nine years prior to Alberti, Brunelleschi applied the modular system with the correct proportions, or as Vitruvius called it in his book: proportio and symmetria. The crossing, a square shape, became the module for the entire church. For instance, the square in the transept arms is repeated three times, and six times in the total length of the nave (see floorplan). A symmetria, or proportion of 1:2, an octave.
For the first time, Florence has columns that fully adhere to classic rules. The architrave of pietra serena that runs through the entire church makes sure that the building is comes across optically as a clear unity. If you stand at the main entrance of the San Lorenzo, you will understand what Michelangelo meant by static architecture that works from the flat plane with one vanishing point at eye level. The perspective effect is overwhelming here, because of the lines in the floor, the lines of the cassette ceiling and the architrave above the arcades. All these lines disappear into one point behind the main altar.
Despite the obvious classical influences, with this truly being a Renaissance church, Brunelleschi does still use the Florentine gothic tradition. There are a number of elements derived from the Santa Maria del Fiore like the white plastered walls, the large round windows in the lunettes and the use of pietra serena for the load-bearing elements like the continuous architrave.
Standing in front of the main altar, at the crossing, you can see a round porphyry plate on the floor surrounded by white marble bands. Cosimo’s tomb lies directly underneath this plate. Three sides of the plate have copper grids made by Andrea del Verrocchio. These allow light to pass into the crypt. The voice of the priest leading the mass and the rays of the monstrance also eminate into the crypt. Such an exclusive location for a burial tomb was unique and anything but modest. Quite a difference from the regular chapels or tombs in the facade of the Santa Maria Novella by Alberti that we examined earlier.
Also, the Medici family is very prominent throughout the rest of the San Lorenzo, and not just in the Old and New Sacristy. For example, the coat of arms of the Medici can be seen in the wooden cassette ceiling in the nave and aisles. It reminded any church visitor that the flag of the Medici ruled over other rich families with a chapel in this church not only in the transept, but also in the nave. Donatello depicted a Pietà at the central panel of one of the two pulpits. The man with the cloak and the woman at the ladder standing against the cross look a lot like Cosimo and his wife. This is particularly evident when you compare this to the marble relief in Berlin and the figures in the fresco in the Medici palace as painted by Gozzoli. We will discuss the pulpit in more detail on the day we examine sculpting in Florence.
The crossing and dome in the San Lorenzo
If you look up near the crossing, you will see a round dome with a lantern (the lantern was built much later) that only allows for a dim light to pass. This dome of the San Lorenzo was definitely not the design of Brunelleschi himself.
Manetti, who arrived in the gallery at the San Lorenzo around 1450, thought that the dome, both in its interior and exterior, was unmistakably not constructed according to Filippo’s design, which is why those who credit it to Brunelleschi find no joy in doing so. He produced his creations under diverse conditions, incorporating various ornamentation and reinforcement techniques, but none of those elements are evident here. In fact, it seems to be the contrary, as the project became increasingly costly and lacked aesthetic appeal both internally and externally. The illumination, the lantern, and the proportions of the components all exhibit deficiencies. For the exact words of Manetti see: Manetti, ‘The life of Brunelleschi by Antonio di Tucci Manetti’, The Pennsylvania State University Press, University Park and London 1271- 1278 (first edition c. 1480).
The two domes of Brunelleschi, a large and a smaller one, which we will examine later in the Old Sacristy, did succeed. These domes take in sufficient light contrary to the dome in the church above the crossing. In his biography, Manetti points out that a better solution was impossible because the crossing pillars were too narrow. The prior, Dolfini, had these pillars erected before Brunelleschi involved himself with the construction of the San Lorenzo. The outside and inside of the dome differ starkly. One of Manetti’s competitors, the young Giovanni da Guaiuole, wrote a letter to Cosimo. In it, he delivers a damning criticism of the dark and ugly dome. One of Cosimo’s friends, Antonio Martelli, even proposed to just tear down this failure altogethern. It is likely that Brunelleschi himself wanted a similar dome as in the Old Sacristy: a ‘melon’ or ‘umbrella dome’.
As you can see, Cosimo dismissed this criticism. Antonio Manetti, however, did respond. His vengeance was sweet. He hired a thug, a man named Barnabo, who beat the poor Giovanni to an inch of his life. Source: Saalman, H., ‘Filippo Brunelleschi The Buildings’, Zwemmer, London 1993 p. 180
The dome of the San Lorenzo barely extends above the gable roof of the transept and the nave. This makes it impossible to place windows in the dome. The setup of the round dome on a square base (the four pendentives ensure the transition) finishes with a square roof. Much different from the umbrella dome at the Old Sacristy which finishes with a round lantern.
Because of the narrow pillars on which the dome rests, Manetti had no other choice but to use this design. For example, this is why the lantern that was added in the 18th century was made of wood. The forces exerted by the dome on the pillars were already significant, and a stone lantern would only make the load worse. The walls surrounding the round dome that support the roof and protect the dome were placed perpendicular to the pillars. This was much needed, as the pillars were able to withstand the downward forces, but not so much the sideward ones. The dome, ‘this failure’, is based on the dome of the Pantheon. For example, rings were attached to the outside of the dome to manage the outward spread (sideward forces).
Furthermore, the thickness of the dome wall decreases as it goes up, just like at the Pantheon. The curvature of the dome is slightly higher than that of a hemisphere. This was done on purpose because the sideward forces would then be slightly less than with a regular hemisphere. Manetti, who never went to Rome, could not have conjured up these refined tricks n. It is likely Alberti gave some directions to ultimately solve the difficult construction issues surrounding the weaker pillars.
At the time when Brunelleschi gets involved in constructing the San Lorenzo, he is tasked with solving the pillars in the crossing. Prior Dolfini placed these pillars with the idea to build a crossing similar to the Santa Croce or the Santa Maria Novella, so without a dome. For any Renaissance architect, and thus for Brunelleschi, a round dome in the square of a crossing was the ideal combination. The pillars of Dolfini, however, would not be able to withstand the force of a dome. Tearing them down and erecting thicker pillars was only a theoretical option given the available finances. Therefore only one solution remained: the pillars were clad on all four sides with fluted pilasters, making the total construction a bit stronger. This fall-back did lead to the transversal arches, which taper toward the crossing pillars at the end of the vault in the aisles, having a somewhat higher curvature than other transversal arches. Still, the difference is so small that it is barely noticeable.
A visually unpleasant connection in the San Lorenzo of chapels and ‘cripple columns and pilasters’.
Next to the unappealing dome, the connection of the chapels at the aisles to the chapels at the transept is just plain ugly. The side chapels overlap the windows of the connecting transept chapels. There is no organic connection between the nave and the transept. Originally, it was not Filippo Brunelleschi’s intention to construct chapels at the aisles next to the nave. But this is exactly what happened. After all, the chapels did yield a fair bit of revenue. The exterior, too, shows that the connection of the nave to the transept is far from appealing.
Vasari added another flaw to this above list of flaws (dome and connection of chapels):
“[…] and many errors are seen therein, one being that the columns are placed on the level of the ground instead of being raised on a dado [plinth], which should have been as high as the level of the bases of the pilasters [the bases of the pilasters between the arches at the side chapels] which stand on the steps, so that, as one sees the pilasters shorter than the columns, the whole of that work appears badly proportioned.’ Translated from:light departed he yielded and rendered therewith his spirit.” Translated from: Giorgio Vasari, ‘De Levens van de grootste schilders, beeldhouwers en architecten Van Cimabue tot Giorgione’, Contact, Amsterdam, 1990 deel I blz. 183 (oorspronkelijke uitgave 1568).
Filippo Brunelleschi would refrain from repeating these mistakes with the Santo Spirito. With this last church, Brunelleschi enjoyed much more freedom, not having to account for what Dolfini had already built, but instead being able to start with a clean slate.