With Soto, his oeuvre is not about mobile objects, but rather is concerned with optical, virtual motion. His investigation focuses on the possibilities to ‘expand’ his sculptural pieces via such optical movement. From the start of the 1950s he works with kinetic backgrounds,striped planes capable of generating a ‘moiré’ effect. Of importance here is not the form itself, but rather what he calls ‘relationships’, relationships between different elements and materials. The ‘relationships’ are followed by what he calls ‘kinetic structures’. Soto constructs works in depth, as it were, by placing staves or other objects (often suspended and without regularity) in front of striped backgrounds, so inducing viewers to shift their position in order to perience ‘optical’ movement. Soto describes himself as a painter and sculptor, not as ‘builder of scale-models for architects’.In contrast to much kinetic art, his work is not based on mathematical or scientific insights, but rather on intuition and experiments in his studio. Soto desires that his works destabilize a viewer’s equilibrium. The scale of his interventions becomes ever greater. At the end of the 1960s he makes Pénétrables, environments of metal rods or nylon threads that go to evoke a ‘total’ feeling of space. Their theatrical character reminds one, oddly enough, of the baroque. If some see a relationship between his works and music, this comes as no surprise. Before he could support himself solely by his art, for years Soto played guitar nightly in the cafés and restaurants of Saint-Germain-des-Prés.