On the Origin of Species Darwin's ideas with those of Lamarck and Goethe while still reflecting the spirit of "Naturphilosophie". Their ambitious programme to reconstruct the evolutionary history of life was joined by Huxley and supported by discoveries in palaeontology. Haeckel used embryology extensively in his recapitulation theory, which embodied a progressive, almost linear model of evolution. Darwin was cautious about such histories, and had already noted that von Baer's laws of embryology supported his idea of complex branching. Asa Gray promoted and defended "Origin" against those American naturalists with an idealist approach, notably Louis Agassiz who viewed every species as a distinct fixed unit
Reactions to On the Origin of Species those defending immutability of species, and in effect said that the book offered the best explanation "ever published of the manner of formation of species", though he did not agree with it in all respects. He still had the gravest doubts that transmutation would bestialise man. It appears that Darwin had assured Owen that he was looking at everything as resulting from designed laws, which Owen interpreted as showing a shared belief in "Creative Power". Darwin had already made his views clearer to others, telling Lyell that if each step in evolution was providentially planned, the whole procedure would be