Esther Ferrer (San Sebastián, 1937), a pioneer and one of the leading representatives of performance art in Spain, began to participate in the activities of the ZAJ group (with Walter Marchetti, Ramon Barce and Juan Hidalgo) in 1967 and, since then, she made action art her main medium, although from 1970 she returned to make plastic works through photographs taken, installations, paintings based on the series of prime numbers or Pi, objects, and so on. Among these works stand out the series of Self-portraits (in process since 1981), Prime Numbers (developed through various spatio-temporal formats), or Educational Toys (1980s). Her work is part of the current of minimalist and conceptual art, started in the sixties of the twentieth century, which has Stéphane Mallarmé, Georges Perec, John Cage or Fluxus as references, as well as in the feminisms of that time.
- Esther Ferrer. En el marco del arte, Marsella, 1993