Groma occupies the place in the synagogue where the scrolls of the Torah were kept inside the curved ark reconstructed by Sol LeWitt. Marisa Merz’s piece of alabaster rested there two years earlier with the Rosa Luxemburg anthem played over loudspeakers by Susan Philipsz. The groma was originally an instrument used by the ancient Romans, and perhaps by others before them, to delimit square lots of land. “The simplicity of its construction fascinated me and the idea of dividing the world into squares terrified me.” The materials of which it is made are to be found everywhere: two crossed sticks and four weights (sacks full of earth or glass jars). It was first produced of the IBA architectural exhibition at the Martin Gropius Bau, Berlin, in 1984, in old SS headquarters. The earth used is certainly steeped in blood. “It recalled the social project of Nazism, and I had woven a very soft but very tough net of copper between the wires.” A second version was exhibited in a richly frescoed room at the Castello di Rivoli in 1989. In “a city constructed precisely with the system of the groma, it indicated an urban perspective but also a certain mentality”. If the earth contained in the bags alludes here to the unending history of the castle designed by Filippo Juvarra, the copper net is replaced with pieces of cloth bearing colored Rorschach blots. The Groma of 1997 was dedicated to Spinoza. The sandbags are replaced with four jars of Murano blown glass containing water that acts as a lens, making it possible to read four lectures delivered by Fabro at the Academy of Fine Arts and inserted into the jars: Una, cento, mille qualità, La sciatteria, Il sospetto, Lo svanire dell’opera dietro la morale, all of 1997. The last jar instead rests on the text of the excommunication decreed by the Jewish community of Amsterdam in 1656. In the work Groma (monoteista) produced for Ostia Antica, finally, the sandbags and glass jars are replaced with four plaster pizzas, one inscribed with the Star of David, one with the Christian cross, and one with the crescent moon. The as yet formless fourth still awaits its symbol. One of the above-mentioned lectures is inserted into each pizza. As Fabro remarks with sarcastic irony, “The idea is a diversion from the chain of tragedy to the food chain.”51