John McCleary is Professor of Mathematics on the Elizabeth Stillman Williams Chair at Vassar College. He received his Ph.D. in mathematics from Temple University, where he completed a thesis on algebraic topology under the direction of James Stasheff. The author of several books, including A User's Guide to Spectral Sequences and Geometry from a Differentiable Viewpoint, McCleary has published extensively on topology, the history of mathematics, and other topics. His current research focuses on algebraic topology – specifically, where algebra reveals what topology may conceal.