Not only was all this of great practical value but its theoretical influence has been incalculable. Linnaeus never saw, and probably would not have dared to proclaim if he had, that the resemblances which made his grouping possible, indicated a relationship based on descent from common ancestors. This was left for men of greater penetration and courage living in a less theological age. Prelates who smiled on the obscene debaucheries of Louis the XV. had Linnaeus’ writings prohibited from papal states, because they proved the existence of sex in plants. Linnaeus not only proved sex in plants but made it the foundation of his classification. He also reminds us that plants were known to be of both sexes by oriental people in early days. Living as they did on the fruit of the date-palms they found it necessary to plant male trees among the females. Their enemies in war time struck a terrible blow when they cut down the male trees, thereby reducing them to famine. Sometimes the inhabitants themselves destroyed the male trees during impending invasion, so that the enemy should find no sustenance in their country; a war measure similar to that of Russians who burned Moscow in the face of Napoleon. In the same year that Sweden produced Linnaeus, France gave birth to Buffon. Rich and independent, he chose to devote a long life to the study of natural history. He had remarkable powers of research and displayed genius in presenting the results of his investigation. But alas! he had less courage than Linnaeus and he lived nearer that terrible enemy of eighteenth century science, the theological department of the University of Paris--the dreaded Sorbonne. As long as he confined himself to the mere description of animals he was a pet of the church, which seems to have pleased him, but when he began to draw evolutionary conclusions of real philosophical import and value, the Sorbonne at once opened its batteries. On these occasions Buffon’s retreat was prompt and unprotesting. It might be remembered as some mitigation of his cowardice that while the reign of the stake and faggot did not extend into the 18th century and there was no danger of the fate of the fearless Bruno, yet so strong was religious bigotry even in this period that Rousseau was hunted out of France, his books burned by the public executioner, and Diderot went to jail. “Hardly a single man of letters of that time escaped arbitrary imprisonment,” says John Morley in his “Rousseau.”