On the Origin of Species by Alfred Russel Wallace, claimed that patterns in the geographical distribution of living and fossil species could be explained if every new species always came into existence near an already existing, closely related species. Charles Lyell recognised the implications of Wallace's paper and its possible connection to Darwin's work, although Darwin did not, and in a letter written on 1–2 May 1856 Lyell urged Darwin to publish his theory to establish priority. Darwin was torn between the desire to set out a full and convincing account and the pressure to quickly produce a short paper. He met Lyell, and in
On the Origin of Species embryonic stages. These factors also supported his theory of descent with modification. The final chapter "Recapitulation and Conclusion" reviews points from earlier chapters, and Darwin concludes by hoping that his theory might produce revolutionary changes in many fields of natural history. He suggests that psychology will be put on a new foundation and implies the relevance of his theory to the first appearance of humanity with the sentence that "Light will be thrown on the origin of man and his history." Darwin ends with a passage that became well known and much quoted: It is interesting to contemplate an entangled