Who said "Form is the expression of content made visible."?

This quote is attributed to Pierre Boulez.

Form is the expression of content made visible. - Pierre Boulez

"Form is the expression of content made visible."

Pierre Boulez Art

Avant-Garde Composer Conductor French 1925–2016

"Music is the vehicle for human emotion. It has always been."

"Compose yourself, and the world will compose itself."

"The serial technique is not a philosophy but a method."

"I think music is the most beautiful of all the arts."

"The stage is my true home."

"Art is the expression of the soul."

"Living well means living properly."

"Art and music are the treasures of civilization"