As to the process and the death of the Prince, the mystery has not yet been removed, and the field is still open to conjecture. It seems a thankless task to grope in the dark after the truth at a variety of sources; when the truth really exists in tangible shape if profane hands could be laid upon it. The secret is buried in the bosom of the Vatican. Philip wrote two letters on the subject to Pius V. The contents of the first (21st January, 1568) are known. He informed the pontiff that he had been obliged to imprison his son, and promised that he would, in the conduct of the affair, omit nothing which could be expected of a father and of a just and prudent king. The second letter, in which he narrated, or is supposed to have narrated, the whole course of the tragic proceedings, down to the death and burial of the Prince, has never yet been made public. There are hopes that this secret missive, after three centuries of darkness, may soon see the light.--[I am assured by Mr. Gachard that a copy of this important letter is confidently expected by the Commission Royale d'Histoire.] As Philip generally told the truth to the Pope, it is probable that the secret, when once revealed, will contain the veritable solution of the mystery. Till that moment arrives, it seems idle to attempt fathoming the matter. Nevertheless, it may be well briefly to state the case as it stands. As against the King, it rests upon no impregnable, but certainly upon respectable authority. The Prince of Orange, in his famous Apology, calls Philip the murderer of his wife and of his son, and says that there was proof of the facts in France. He alludes to the violent death of Carlos almost as if it were an indisputable truth. "As for Don Charles," he says, "was he not our future sovereign? And if the father could allege against his son fit cause for death, was it not rather for us to judge him than for three or four monks or inquisitors of Spain?" The historian, P. Matthieu, relates that Philip assembled his council of conscience; that they recommended mercy; that hereupon Philip gave the matter to the inquisition, by which tribunal Carlos was declared a heretic on account of his connexion with Protestants, and for his attempt against his father's life was condemned to death, and that the sentence was executed by four slaves, two holding the arms, one the feet, while the fourth strangled him. De Thou gives the following account of the transaction, having derived many of his details from the oral communications of Louis de Foix: