man.’ The treatise shows him to be an adept in popular exposition and appeal. In 1675 he published the last of his books strictly relating to religion, viz. ‘The Interest of Reason in Religion, with the Import and Use of Scripture Metaphors, and the nature of the Union betwixt Christ and Believers, with Reflections on a Discourse by Mr. Sherlock.’ Ferguson's skill as a religious controversialist, and his influence with the dissenters, strongly recommended him to the party of Shaftesbury, and he now came forward as the champion, against the government, of the cause of protestantism. His first political pamphlet, entitled ‘A Letter to a Person of Honour concerning the “Black Box,”’ was published anonymously with the date London, 15 May 1680. It had reference to a missing ‘Black Box,’ reported to contain proofs of the king's marriage to Lucy Walters, the mother of the Duke of Monmouth. The position taken up by Ferguson was that the whole story of the ‘Black Box’ was a fiction invented by those who wished to discredit the Duke of Monmouth's title to the crown, and to divert attention from the treasonable procedure of the Duke of York. It shows great skill in the means chosen to arouse popular prejudice against the Duke of York. On 2 June Charles disavowed the marriage ‘on the faith of a Christian and the word of a king,’ and on the 10th Ferguson published ‘A Letter to a Person of Honour concerning the King's disavowing his having been married to the Duke of Monmouth's Mother,’ in which he hinted that evidence would be forthcoming of the marriage ‘when the matter shall come before a competent judicature.’ The controversies connected with the exclusion bill occasioned the following pamphlets from his pen: ‘Reflections on Addresses,’ ‘Smith's Narrative,’ ‘A Vindication of Smith's Narrative,’ ‘Reflections on the Jesuits who suffered for the Plot,’ and ‘The Just and Modest Vindication, in answer to King Charles's Declaration on his Dissolving the English Parliament,’ republished with additions and alterations under the title ‘The Design of Enslaving England Discovered.’ After a city of London jury on 24 Nov. 1681 had thrown out a bill indicting Shaftesbury of high treason, a pamphlet appeared entitled ‘No Protestant Plot, or the present intended Conspiracy of Protestants against the King and Government discovered to be a Conspiracy of the Papists against the King and his Protestant Subjects.’ It was extended into a second and a third part. The authorship of the first two parts has usually been ascribed to Shaftesbury, but Ferguson claims the authorship of the whole three. He is also said to have been the author of the second part to Andrew Marvell's ‘Rise and Growth of Popery,’ 1678, giving an account of its growth, 1678–82. The pamphlet is stated to be printed at Cologne, 1682, but was really printed at London (Wood, Athenæ, iv. 232).
Ferguson has generally been regarded as one of the chief contrivers of the Rye House plot, and even he himself admits, in the words of his apologist, that ‘he conducted the communications between Monmouth, Russel, and those who acted with them, and the more ruthless coterie of conspirators’ (Ferguson, Ferguson the Plotter, p. 64). According to his own narrative, however (ib. 409–37), he took charge of the arrangements only the more successfully to frustrate it. The failure of the plot in October 1682 was, according to Ferguson, brought about by his designedly delaying to make arrangements for it till the king had returned from Newmarket. His aim all along, if he is to be believed, was to substitute an insurrection for assassination, and the new project was now prosecuted with the utmost vigour. After several meetings had been held information regarding the movement was conveyed to the government by Colonel Rumsey, who had attended a meeting uninvited. Ferguson made his escape with Shaftesbury to Holland, where, 21 Jan. 1683, he was present at Amsterdam at the death of the earl, who left him a legacy of 40l. He was supposed to have written a vindication of the association, which was seized in the hands of his servant as he was going with it to press in the beginning of December 1682 (Wood, Athenæ, iv. 80). In February Ferguson returned to London three or four days before the court went to Newmarket. He again, according to his own admission, had a principal share in the arrangements in connection with the second assassination plot, but it also, he asserts, was frustrated simply by his skilful management, and not, as was at the time supposed, by the fact that the king, owing to a fire, left Newmarket sooner than he intended. Had there been no fire, and had the king remained there a month longer, ‘he would,’ Ferguson asserts, ‘have come back in as much security, and as free from danger of being assaulted upon the road, as at the time he did.’ Ferguson was undoubtedly morally as well as legally involved in the scheme. After the frustration of this second plot Ferguson became a leading adviser in connection with the insurrection schemes of Argyll and Monmouth. On the failure of the plot he had fled north to Scotland, and afterwards taking ship thence to Hamburg arrived in Holland. There he wrote ‘An Enquiry into a Detection of the
