He who will go thus far, ought not to hesitate to go one step further, if he finds on finishing this volume that large bodies of facts, otherwise inexplicable, can be explained by the theory of modification through natural selection;
Puntu honeteraino heldu denak ez du zalantzatan ibili behar beste pauso bat egiteko, baldin, liburu hau bukatzean, aurkitzen badu hautespen naturalaren bidezko eraldaketaren teoriaren bitartez esplika daitezkeela bestela esplikaezinak diren egitate multzo handiak;