the work done by natural agents on the rock, Penone highlights the similarities between the action of the river and the action of the sculptor, thus identifying himself with the river. He wrote: "Picking up a stone worn by the river, going back up the course of the river to discover the point in the hills from which the stone came and hewing a new block of stone from the mountain and then exactly replicating the stone picked up in the river in the new block of stone: this is to be a river. Producing a stone made of stone is perfect sculpture, a return to nature, it is a cosmic heritage, pure creation, the naturalness of a good sculpture acquires a cosmic value. Being a river is the true stone sculpture." Some of Penone's works produced between 1979-1980 such as Albero d'acqua ("Tree of Water") and Colonna d'acqua ("Column of Water), all stem from the same logic of superimposing liquid on liquid vertically. "The condition of water is horizontality, the condition of verticality is sculpture, raising the water is a poetic gesture," he wrote in 1976. He sees all elements as fluid and what we would describe as hard or soft depends only on the state in which we find ourselves acting. In Gesti vegetali ("Vegetation Gestures"), a series of sculptures which Penone began to work on in 1982, Penone "fossilized" the imprints of his hands on strips of clay stuck to a dummy that served as a frame. He then cast the clay in bronze using the lost-wax technique and completed the work by placing the casts next to each other so as to create the semblance of a human being. Gesti vegetali ("Vegetation Gestures") was first displayed in exhibitions at the Museum of Contemporary Art of Chicago and the Musée d'Art Moderne de la Ville de Paris in 1984. "Fossilized gestures that have been performed in a space," wrote the artist in 1977, "bring man closer to plants, which are compelled to live eternally under the burden of the gestures of their past." In his installation in Basel's Merian Park in 1984, he began to engraft vegetation onto his sculptures, as appears in his solo exhibition at the Marian Goodman Gallery in New York in 1985. Penone has made bronze trees which have been erected in various public spaces. One example is the Pozzo di Münster ("Well