This work is registered in the Archivio Enrico Castellani, Milan, under no. 91-007.
‘Space interests us and concerns us because it contains us. I use monochrome surfaces, as immaterial as possible and shaped to form double curves with repeated elements: a series of points in relief and points forming depressions, negative and positive poles, and a series of minimal operative interventions. (…) Reality, too, always has an obverse and a reverse that, by fitting together, deny each other in turn’ (E. Castellani, quoted in ‘Ambiente bianco. 1967’, in Lo spazio dell’immagine, Venice 1967, p. 78).