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We show in this article how Girard Desargues, in his well known text onconics, the \textit{Brouillon Project,} manages to use Menelaos' theorem withsome awesome virtuosity. To this end, we propose a detailed analysis of his\textit{combinatorial} approach, which was already visible in the developmentof his notion of involution. We shall study the proofs of two importanttheorems of the \textit{Brouillon.} The first is the theorem of the "ram\'ee",stating that the configuration of involution is invariant by perspectiveprojection, and the second is the great theorem of Desargues on pencils ofconics. We shall also study in the same spirit the first lemma (dealing withthe hexagram) of the \textit{Essay pour les coniques} by Pascal and the\textit{Advis charitables} by de Beaugrand.

L'usage de la combinatoire chez Girard Desargues : le cas du th\'eor\`eme de M\'en\'ela\"us