Sometimes wrong but rarely in doubt, Stephen Jay Gould was a 19th century naturalist plunked down in the 20th century. His most notable scientific achievement was the theory of "punctuated equilibria" (co-authored with Niles Eldredge), arguing that species don't evolve gradually, as the conventional wisdom suggested, but rather remain unchanged for long periods, then undergo rapid bursts of change. His papers, essays, books and lectures brought Gould's wide-ranging intellect to the attention of the public—while burying his intellectual opponents under the weight of millions of words. Along the way, the politically left-wing scientist, in frequent and passionate writing on baseball, proved to admirers of George Will that conservatives have no monopoly on the love of our national sport. Gould delighted his fans and set his enemies' teeth gnashing, but even the latter had to admit he forced them to think.

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