He was at times a bold thinker; but his prudence, not to say timidity, in presenting in his ironical way his thoughts on the origin of things, is annoying, for we do not always understand what Buffon did really believe about the mutability or the fixity of species, as too plain speaking in the days he wrote often led to persecution and personal hazard.[125] His cosmological ideas were based on those of Burnet and Leibnitz.

His geological notions were founded on the labors of Palissy, Steno, Woodward, and Whiston.

He depended upon his friend Daubenton for anatomical facts, and on Gueneau de Montbeliard and the Abbe Bexon for his zooelogical data.

As Flourens says, "Buffon was not exactly an observer: others observed and discovered for him.

He discovered, himself, the observations of others; he sought for ideas, others sought facts for him." How fulsome his eulogists were is seen in the case of Flourens, who capped the climax in exclaiming, "Buffon is Leibnitz with the eloquence of Plato;" and he adds, "He did not write for savants: he wrote for all mankind." No one now reads Buffon, while the works of Reaumur, who preceded him, are nearly as valuable as ever, since they are packed with careful observations.
The experiments of Redi, of Swammerdam, and of Vallisneri, and the observations of Reaumur, had no effect on Buffon, who maintained that, of the different forms of genesis, "spontaneous generation" is not only the most frequent and the most general, but the most ancient--namely, the primitive and the most universal.[126] Buffon by nature was unsystematic, and he possessed little of the spirit or aim of the true investigator.