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 & Natural (as far as Final Causes & Design are concerned) on the other. The range & mass of knowledge take away one's breath." To Fanny Wedgwood she wrote, "I rather regret that C.D. went out of his way two or three times to speak of "The Creator" in the popular sense of the First Cause... His subject is the 'Origin of Species' & not the origin of Organisation; & it seems a needless mischief to have opened the latter speculation at all – There now! I have delivered my mind." The Revd. Adam Sedgwick had received his copy "with