On the shoreline of the Nabor Carrillo artificial lake there is a barrier of made of red tezontle rocks, underpinned and organized, fitting one upon the other and forming a railing that rises one meter above the lake’s water level. This parapet is held together merely by the correspondence of concavities and convexities between rocks. A group of farmers from the Texcoco region built this parapet to create a barrier that would prevent water from overflowing during rainy seasons. From a bird’s eye, airplane or satellite view, the parapet of rocks can be seen forming a perfect rectangle, a red line framing a mirror of dark waters. The rocks composing this line, broken by chisel into pieces of similar size and fit together by human hands, were torn from the earth to enter the domain of human agency. The rock’s displacement from the quarry to the parapet forces it out of a realm into another; it becomes an element fractionated by chisels, weighed, measured, and arrayed; it is then bought by someone, to become a mere item on an inventory of agricultural goods, part of the Mexican Federal Government’s accounting documents. [...]