The Venice Biennale of Art grows bigger every year, and this year’s 55th edition includes 88 countries and 158 artists. The show’s exceptionally young curator, Massimiliano Gioni (born 1973 near Milan, current curator of the New Museum in New York), found a slightly demented idea for harnessing the inevitable heterogeneity of works that end up in such international exhibitions: the little-known utopian project for the Palazzo Enciclopedico by Marino Auriti (1891-1980), an architectural image that serves as the Biennale’s underlying allegory. Auriti, who emigrated from Italy to the United States during the first years of Fascism and worked the rest of his life as a mechanic outside Philadelphia, in his spare time produced an exquisite model for his preposterous monument to knowledge: a 136-story structure (30 stories short of Burj Khalifa in Dubai), which he proposed in 1955 be built on the Washington Mall. This towering folie, with its corner cupolas, pergolas and stepped profile, now greets visitors at the entry to the Venice Arsenale’s Corderia as an invitation to consider other efforts to capture the totality of knowledge...