From V.I. Arnold's Experimental Mathematics:
Not having achieved what they desired, they pretended to desire what they had achieved.
–M. Montel
Who is M. Montel? Is he related to the French mathematician Paul Montel. Or is it the same person? Does M. stand for Monseigneur?
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If the quoted phrase is about mathematics, certainly it is of Paul Montel the M. corresponding to"Monsieur". Apparently, as far as I know, the name of Paul Montel does not appear practically never in English books. But in the French school there is even the adjective "montelian". A Montel space, for example, is in France a locally convex metrizable, complete space in which every bounded subset is relatively compact. For example the space of holomorphic functions on an open $U\subset \mathbb C^n$ provided with the topology of compact convergence is Montel.
The "Montel" cited by Arnold is almost surely Paul Montel, the only one of his name who has gained posterity. It was an usage, say till the fifties, not to use that much given names "Hilbert has proved", not "David Hibert...". You will find many instances in old texts where people are reverently called "M. Hilbert" or "Herr Hilbert" :)