Utopia Parkway: The Life and Work of Joseph Cornell by Deborah Solomon:
It was at the Hippodrome that Cornell had the chance to see Harry Houdini, who escaped from chains and a locked safe, and made elephants vanish into thin air. Houdini’s act turned out to be the most memorable performance of Cornell’s youth; the magician would loom over his childhood as a symbol not only of inspired entertainment but of artistic possibility as well. For art, as much as a magic show, can be a disappearing act, and the notion of vanishing was central to the young Cornell’s imagination. The metal rings and suspended chains that would later become common elements in his boxes refer at least partly to Houdini and the memory of a lonely boy who wished to vanish from the shackles of day-to-day reality. And the very form of the box was already intriguing to Cornell; whereas Houdini escaped out of boxes, Cornell would one day escape into them.