Thus, of the very numerous writers who have advanced this opinion, some, such as Baron d’Heiss, M. de Chambrier, M. Depping, and M. Camille Rousset, have done so by only taking account of the circumstances accompanying the abduction, by invoking probabilities, and by showing a preference. Others, such as Roux-Fazillac, Reth, and Delort, have endeavoured to support their demonstrations with more precise and less general proofs, not occupying themselves exclusively with the arrest of this individual, but with the captive’s existence and his changes of prison. They have, in a word, attempted to follow him without losing sight of him for an instant, from the moment of his incarceration to that of his death. How have they succeeded? A very sagacious writer, M. Jules Loiseleur, has, for some years past, applied the processes of a rigorous historical criticism and the qualities of a penetrative mind to some of those secondary questions which the historian often neglects or avoids, either because they would retard the rapidity of his progress, or because their exact solution would perhaps be contrary to the general theory upon which the _ensemble_ of his task has been conceived. These species of minute inquiries, pursued according to a judicial model, concentrate the attention upon certain points, isolated from all others, and present, with some inconveniences, some precious advantages. For, if by such a process, we cease to take account of the necessary influence of general facts, if the marvellous chain of causes and effects be a little neglected, this method, in return, assures to him who employs it entire liberty to study the question under all its phases, and above all things frees him from any preconceived idea, from the necessity of sacrificing himself to a theory, or of obeying too servilely the conditions of art or the sovereign rules of proportion. It is thus that M. Loiseleur has studied,[550] by introducing new documents into the discussion, the question of the pretended poisoning of Gabrielle d’Estrées and of the supposed marriage of Anne of Austria and Mazarin. The problem of the Man with the Iron Mask has also attracted the scrupulous attention and meditations of this trained mind. M. Loiseleur has not brought forward any new documents in considering this question. It is to those already published that he has directed his examination, and to the theory that makes Matthioly the Man with the Iron Mask.[551] The following is the first result of his observations.