The title of this work, which Duchamp said he "intended to sound like an oculist’s prescription," tells the viewer exactly how to look at it. But peering through the convex lens embedded in the work’s glass "for almost an hour” would have a hallucinatory effect, the view being dwarfed, flipped, and otherwise distorted. Meanwhile the viewer patiently following the title's instruction is him- or herself put on display for anyone else walking by. Duchamp called To Be Looked At . . . his "small glass," to distinguish it from his famous Large Glass of 1915–23. He made the work in Buenos Aires, Argentina, where he had fled earlier in 1918 to escape the oppressive atmosphere of the United States during World War I. When he shipped it back to New York, the glass cracked in transit, an effect that delighted him.
from Inventing Abstraction, 1910–1925, December 23, 2012–April 15, 2013