A History of Evolution by Carroll Lane Fenton

Henry Fairfield Osborn, noted evolutionist and paleontologist, divides the evolutionists of the seventeenth and eighteenth centuries into three groups -- the natural philosophers, the speculative writers, and the great naturalists.

The speculative writers were a heterogenous group of men, partly philosophers, partly naturalists, and partly of various other professions. They were, in the main, untrained in accurate, inductive, scientific investigation, and depended upon the Greeks for most of their theory. They differed from the philosophers, some of whom we have already studied, in that their ideas were boldly advanced without any support of observation, or the slightest regard for scientific methods. Some of them were, for their day, immensely popular writers, and their trashy books, filled with myriads of impossible "facts," undoubtedly did a great deal to block the progress of true evolutionary studies. Just as the public today does not distinguish between the would-be orator who talks of the "facts" of natural selection, and the true evolutionist, and ridicules both, so the public the eighteenth century linked the speculators with the sincere, hard-working naturalists, and declared the ideas of both to be foolish and blasphemous.