Georges-Louis Leclerc, Comte de Buffon
Buffon's Natural History (1797) Vol. 10, pp. 340-341 https://books.google.com/books?id=respAAAAYAAJ&pg=PA340, an English translation of Histoire Naturelle (1749-1804).
Georges-Louis Leclerc, Comte de Buffon was a French naturalist, mathematician, cosmologist, and encyclopédiste.
His works influenced the next two generations of naturalists, including Jean-Baptiste Lamarck and Georges Cuvier. Buffon published thirty-six quarto volumes of his Histoire Naturelle during his lifetime; with additional volumes based on his notes and further research being published in the two decades following his death.Ernst Mayr wrote that "Truly, Buffon was the father of all thought in natural history in the second half of the 18th century".Buffon held the position of intendant at the Jardin du Roi, now called the Jardin des Plantes.
Wikipedia

Georges-Louis Leclerc, Comte de Buffon
Buffon's Natural History (1797) Vol. 10, pp. 340-341 https://books.google.com/books?id=respAAAAYAAJ&pg=PA340, an English translation of Histoire Naturelle (1749-1804).
Georges-Louis Leclerc, Comte de Buffon book Histoire Naturelle
Histoire Naturelle (1753), trans. J. S. Barr, London: H. D. Symonds, 1797, vol. V, pp. 209 https://books.google.it/books?id=9QpTAAAAYAAJ&pg=PA209-210.
“Never think that God's delays are God's denials. Hold on; hold fast; hold out. Patience is genius.”
Georges-Louis Leclerc, Comte de Buffon
As quoted in New Cyclopædia of Illustrations (1870) by Elon Foster, p. 492
“Genius is nothing else than a great aptitude for patience.”
Georges-Louis Leclerc, Comte de Buffon
La génie n'est utre chose qu'une grande aptitude à la patience. <br class="br">Narrated by Herault de Séchelles ( La visite à Buffon, ou Voyage à Montbard http://www.atramenta.net/lire/voyage-a-montbard/3508, 1790), when speaking of a talk with Buffon in 1785. (Not in Buffon's works.) Reported in Bartlett's Familiar Quotations, 10th ed. (1919).
Georges-Louis Leclerc, Comte de Buffon book Histoire Naturelle
Le style c'est l'homme.
Discourse on taking his seat in the French Academie (Aug. 25, 1753). Le style c'est l'homme même. Œuvres Completes (1778). Histoire Naturelle (1769). Le style est de l'homme. Discours sur Style.