Pierre Louis Moreau de Maupertuis (1751. Essay de Cosmologie) stated the idea of natural selection or the survival of the fittest early and sub-headed his essay: "Which examines the evidence for God's existence from the Wonders of Nature." That is, it is an early example of the old combination of natural selection with fixed species:
“Mais ne pourroit-on pas dire, que dans la combinaison fortuite des productions de la Nature, comme il n'y avoit que celles où se trouvoient certains rapports de convenance, qui pussent subsister, il n'est pas merveilleux que cette convenance se trouve dans toutes les eípèces qui actuellement existent? Le hazard, diroit-on, avoit produit une multitude innombrable d'Individus; un petit nombre se trouvoit construit de manière que les parties de l Animal pou voient íàtisfaire à ses besoins; dans un autre infiniment plus grand, il n'y avoit ni convenance, ni ordre: tous ces derniers ont péri: des Animaux sans bouche ne pouvoient pas vivre, d'autres qui manquoient d'organes pour la génération ne pouvoient pas se perpétuer: les seuls qui sòient restés sont ceux où se trouvoient l'ordre & la convenance & ces espèces, que nous voyons aujourd'hui, ne sont que la plus petite partie de ce qu'un destin aveugle avoit produit.” (Maupertius 1751. Essay de Cosmologie, p. 24-26)This passage is often, falsely, attributed to Maupertuis' earlier publication Venus Physique. Its reproduction is then, typically, deviant (e.g., starting with "Ne pourrait-on" instead of "Mais ne pourroit-on") and cited without giving page numbers. Anyway, the above passage roughly translates:
“Could one not say that, in the fortuitous combinations of the productions of nature, none but those that found themselves in certain relations of appropriateness could subsist, is it not wonderful that this appropriateness is present in all the species that are currently in existence? Chance, one would say, produced an innumerable multitude of individuals; a small number found themselves constructed in such a manner that the parts of the animal were able to satisfy its needs; in another infinitely greater number, there was neither appropriateness nor order: all of these latter have perished. Animals lacking a mouth could not live; others lacking reproductive organs could not perpetuate themselves: the species we see today are but the smallest part of what blind destiny has produced.”Some internet sources translate "convenace" with "fitness" instead of "appropriateness," in order to make the semblance clearer.
The fact that the principle of natural selection was understood at that early time shows that Darwin, Wallace or Matthew, for that matter, did not 'discover' the mechanism of natural selection from scratch, as if it fell from heaven and into their heads. They rather combined an old mechanism with the opposite of what it was previously believed to do. In the new combination, it suddenly made species transform, where previously it kept them fixed.
While this was an extremely important new idea (new combination of old ideas) that made many people see evolution going on where, before, they had seen creation, it is a very small step in retrospect. In retrospect, one could deny that anything new had been proposed by these pioneers,by simply pointing out that both parts of the new combination have been old. A particularly egregious example of this frame of mind cane be found here.