With respect to the mysterious part of the letter, where he speaks of one word which would be of such infinite importance, it is difficult, if not rather utterly impossible, to explain it by any rational conjecture.  Mr. Macpherson’s favourite hypothesis, that the Prince of Orange had been a party to the late attempt, and that Monmouth’s intention, when he wrote the letter, was to disclose this important fact to the king, is totally destroyed by those expressions, in which the unfortunate prisoner tells his majesty he had assured the Prince and Princess of Orange that he would never stir against him.  Did he assure the Prince of Orange that he would never do that which he was engaged to the Prince of Orange to do?  Can it be said that this was a false fact, and that no such assurances were in truth given?  To what purpose was the falsehood?  In order to conceal from motives, whether honourable or otherwise, his connection with the prince?  What! a fiction in one paragraph of the letter in order to conceal a fact, which in the next he declares his intention of revealing?  The thing is impossible.

The intriguing character of the Secretary of State, the Earl of Sunderland, whose duplicity in many instances cannot be doubted, and the mystery in which almost everything relating to him is involved, might lead us to suspect that the expressions point at some discovery in which that nobleman was concerned, and that Monmouth had it in his power to be of important service to James, by revealing to him the treachery of his minister.  Such a conjecture might be strengthened by an anecdote that has had some currency, and to the truth of which, in part, King James’s “Memoirs,” if the extracts from them can be relied on, bear testimony.  It is said that the Duke of Monmouth told Mr. Ralph Sheldon, one of the king’s chamber, who came to meet him on his way to London, that he had had reason to expect Sunderland’s co-operation, and authorised Sheldon to mention this to the king:  that while Sheldon was relating this to his majesty, Sunderland entered; Sheldon hesitated, but was ordered to go on.  “Sunderland seemed, at first, struck” (as well he might, whether innocent or guilty), “but after a short time said, with a laugh, ’If that be all he (Monmouth) can discover to save his life, it will do him little good.’” It is to be remarked, that in Sheldon’s conversation, as alluded to by King James, the Prince of Orange’s name is not even mentioned, either as connected with Monmouth or with Sunderland.  But, on the other hand, the difficulties that stand in the way of our interpreting Monmouth’s letter as alluding to Sunderland, or of supposing that the writer of it had any well-founded accusation against that minister, are insurmountable.  If he had such an accusation to make, why did he not make it?  The king says expressly, both in a letter to the Prince of Orange, and in the extract, from his “Memoirs,” above cited, that Monmouth made no discovery of consequence,