In history there are moments when everything seems to merge into a single chord and something completely new appears. One such moment took place in New York in the early 1950s when, in the words of Morton Feldman, "for a brief moment no one pretended to know what art was about." New territories were discovered simultaneously in the field of painting, music, dance and literature. While abstract expressionism shocked the art world with its large canvases, the spontaneity of its strokes and its colors, Morton Feldman was, along with John Cage, who best embodied the field of music this search outside of traditional values .

It was in this cultural climate that Feldman began to compose music that lived in an intermediate zone, between categories: between the visual and the auditory, between time and space. Through new open and experimental notation systems, and the implementation of methods of chance, he set out to free sound from musical rhetoric and the composer's control. He thus arrived at a non-figurative notion of music, abstract and concrete at the same time. He tried to go even further, by conceiving a sound without origin or source, something as paradoxical as the sound of an abstract instrument. He became a composer of "time canvases", who sought to translate into the auditory plane the states of tension and immobility typical of Rothko's paintings, the immediacy and expressive urgency of Pollock's action painting techniques, and the hesitant and adventurous brushstrokes of Guston.

Thoughts vertical, the first complete edition in Spanish of Feldman's writings, brings together a large number of essays, lectures, anecdotes, interviews, program notes and unpublished texts in which the composer reflects on his own work, while portraying the scene New York artist of the fifties and traces an original aesthetic lineage, not strictly musical, in which composers like Schubert, Varèse or Cage, writers like Frank O'Hara and painters like Mondrian or della Francesca all gravitate in the same way.