This is the final of three reviews of MIT Press books in The Vienna Series in Theoretical Biology dealing with convergent evolution, something I consider to be one of evolutionary biology’s most exciting topics. Are evolutionary changes happy accidents, i.e. contingencies? Or is there a law-like repeatability underneath, explaining why some traits evolve time and again, i.e. convergence? Is it even a matter of either-or? And what lessons does this hold for life elsewhere in the universe? Philosopher Russell Powell wrestles with these questions in a manner that is as rigorous as it is intellectually rewarding. Evolutionary biologists will want to give this excellent book a very close read.