A Skywriting airplane writes the word ‘Boezem’ with condensation trails in the cloudy sky above Amsterdam's harbour. After some time the word begins to blurr, and ultimately disappears behind a cloud bank. The happening can be conceived as signing the cosmos, but because the signature is sure to disappear, it appears the artist is distancing himself from this pretentious act. Boezem does not presume to that, and does not confer upon the firmament the aura of an artwork; he is only confirming his discovery in 1963 of air, weather and wind as visual material. The action is more important than the result. The signature on the heavens is a sign of the expansion of the context of art and a commentary on the rather limited space that is traditionally assigned to artworks. In the three panoramic photographs, the passage of time between the appearance and dissapearance of the signature remains as a visible souvenir of this airshow. The photographic record, which was created through a process in which time is an important factor, is an essential part of the artwork. The photographs were damaged on June 9, 1993, during a move from Toulon to Paris. The panels were restored in the Ateliers de la Ville de Paris under the responsibility of Anne Cartier-Bresson.