Raymond Ayoub quoted Legendre in his paper on the early history of elliptic functions(The Lemniscate and Fagnano's Contributions to Elliptic Integrals,1984):

...lucky events which do not arise except to those who know how to give them birth.

G. N. Watson also referred to a similar text in his paper "The Marquis and the Land-agent; a Tale of the Eighteenth Century":

...as Legendre once remarked in another connection, occur only to those who know how to produce them.

Question: What is Legendre's original text of these quotations?