Stephen J. Gould s greatest contribution to science is a revised version of the theory of evolution which offers today a useful framework for understanding progress in many evolutionary fields. His intuitions about the conjunction of evolution and development, the role of ecological factors in speciation, the multi-level interpretation of the units of selection, and the interplay between functional pressures and constraints all represent fruitful lines of experimental research. His opposition to the progressive representations of evolution, the gene-centered view of natural history, or the...