How to approach or build a sound image from a completely unknown material? What decisions must the interpreter make to bring this image to life? In an attempt to answer these questions, Pianists and the Music of their Time: Facing the Unknown is based on a series of interviews with renowned pianists (Claude Helffer, Roy Howat, Ursula Oppens, Ian Pace, Anne Piret) responsible for the creation of works by Elliott Carter, Claude Debussy, André Riotte and Iannis Xenakis. The pianists' discourse is illustrated by musical examples, linking the visible, that's to say, the score as a starting point and reference point, and the invisible, meaning the music transmitted by the composers to the performers. The individuality of their choices, and certain similarities, emerge: the combination of several analytical methods based on an unconventional approach; the implicit presence of gesture, crucial for the elaboration of the musical discourse in concert; the open-mindedness; the desire to discover the music composed around them; the availability to present it to the public. As these characteristics have been observed throughout history, a perspective is offered on the beginning of the 20th century, with the press of the time reflecting the important changes in musical language, but also in the criteria of listening and taste: by comparing the reactions and practices of the 20th and 21st centuries facing the unknown, the author guides the reader into the heart of a vast, unexplored universe of sound.