... of this old and ancestrally-knotty family have all descended from two or three of the hardier varieties. He arrives at this conclusion from a geographical survey of what he would call the "whole field of distribution," and "the probable historical connection between these congeneric species." But science should deal with as few probabilities as possible, especially where experience furnishes no guide to certainty, and only the remotest clue to likelihood. We should never predicate probabilities ... — Life: Its True Genesis • R. W. Wright
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