Descartes and Augustine: creation of eternal truths

It is only rather late that Descartes, in his letter to Mesland dated May 2, 1644, claims his debt to Augustine to acknowledge not the creation of eternal truths but the coincidence within God of willing, seeing and doing. Hence the question : what is truly the debt owed to Augustine when one considers the doctrine exposed to Mersenne in 1630? After having shown that Augustine claims neither the creation of eternel truths, nor coincidence within God of willing, seeing and doing, the author questions what may be at stake in such a reference which - replaced within its context - is quite reasonably grounded.