Kästner was impressed by Schnabel and published after his death a poem about him in the book "Dr. Erich Kästners lyrische Hausapotheke" (1936). Later Schnabel was mentioned as one example for "the funny Germans" in an anthology. "The easy is the most difficult" is a famous word of Schnabel and it also became the principle of his life: Schnabel mostly experimented on everyday objects trying to improve them. Especially his simplistic food cutleries, which reached from a mixture between fork and knife up to a fork with only one prong became virtually legendary. Earning laughs for such inventions in his lifetime, today there are in more extensive cutlery sets not seldom found parts which are not unlike the Schnabel-Inventions around the turn of the century. Nevertheless it seems to be possible, that Schnabel never wanted to invent useful objects and must be seen as a kind of early performance artist. Who's That Girl World Tour  The Who's That Girl World Tour (also billed as Who's That Girl World Tour 1987) was the second concert tour by American singer and songwriter Madonna. The tour supported her 1986 third studio album "True Blue", as well as the 1987 soundtrack "Who's That Girl". It was Madonna's first world tour, reaching Asia, North America and Europe. Musically and technically superior to her previous initiative, the Who's That Girl Tour incorporated multimedia components to make the show more appealing. Madonna trained physically doing aerobics, jogging and weight-lifting, to cope with the choreography and the dance routines. For the costumes, she collaborated with designer Marlene Stewart, expanding on the idea of bringing her popular video characters to life onstage, reworking scenes from her music videos. The stage had four video screens, multimedia projectors and a flight of stairs in the middle. Patrick Leonard, who was the music director, encouraged Madonna to go with the idea of remixing and presenting her older songs for the show. The title Who's That Girl came to Madonna's mind when during rehearsals one-day she looked at a gigantic image of herself, projected on a screen on the stage. The show consisted of seven costume changes, with song-and-dance routines, theatrics and addressing social causes. The tour was critically appreciated, with reviewers commending the extravagant nature of the concert and Madonna as a performer. It was a commercial success, grossing in total of US$25 million ($ million in dollars) by playing in front of 1.5 million audience.