The Swiss-born artist Paul Klee (1879-1940) painted with his left hand and wrote with his right and with both hands could draw and write simultaneously, “taking his line for a walk”, as he put it. His paintings often depicted the world as he believed the modern artist should, in a language of lines, signs, symbols, formulas and rhythms that went to the deeper meaning of things. Logical yet irrational, intellectual yet mystical, apparently childlike yet carefully constructed, often slyly humorous, many of his paintings have inspired composers, among them Pierre Boulez, who wrote a book about Klee in 1989, The Fertile Country (named after Klee’s painting of the fields around the Nile).

Klee was an accomplished semi-professional musician, born into a musical family; his German father was a music teacher, his Swiss mother a singer. Until the age of 19, when he opted for art and moved to Munich to study painting, he envisaged making the violin his career. After a long courtship, he married a pianist, Lily Stumpf. His other link to the theatre is more psychological: Klee was a wry observer of humankind; his diaries reflect the ironic distance with which he studied friends, strangers and himself. He was known to take his opera glasses on walks so as to observe people on the sly.