40,000 nails (2018) permanently marks the second cell on the third floor of the Le Murate Complex after the long work carried out on commission by the RIVA Project for the QUI solo show (2018). The wall, meant as a geographical map of a iction, took shape gradually, as the work progressed and as the wall reacted, collapsing under the blows of the hammer and the wounds caused by the nails. In this place of seclusion and, at a later stage, of confinement, Masi wanted to reproduce the forced bond of the persons living in those cells, the prisoners of those hostile walls that were anyway the only element of the outer world the convicts could deal with. Hence the contraposition with the river, which is instead in constant flow, whose waters never inhabit the same place.