The declaration is a hypothesis, one with which any seasoned professional would not agree. Whatever its merit as philosophy, the Newtonian dictum had a very great political value, as it drew the line clearly between the realms of religion and science. It was, in effect, a division of the world of thought. Newtonian physics and scientific methodology established themselves quickly as the foundation of modern science. Given the severely materialistic nature of the foundation, it is not surprising that the biology which proved most convincing, most acceptable to nineteenth century scientists, was Darwinian materialism.
Species come from other species by mechanical means.
Darwin himself nodded occasionally to the Creator, as the original source, but his followers did not follow him in this deference. Darwinism acquired the reputation of being a refutation of the God concept. In the early and mid-nineteenth century, scientists had no inkling of the existence of genes. The discovery of the specific physical mechanism of reproduction had to wait upon the refinement of the microscope. The first laws of heredity, including Mendel's Laws, were set forth in 1900.