The duke d'Aveiro, one of the greatest men in the kingdom, was the ostensible chief of this conspiracy; whilst the marchioness de Tavora, a most distinguished character at court, was in fact the principal agent; and the whole was conducted by father Malagrida, a member of the most powerful religious order in the Christian world. The union of persons so differently situated, and of such opposite characters, was the effect of a concatenation of circumstances of the most extraordinary nature. The duke d'Aveiro was descended from the younger branch of the family of Mascarenhas, which, though one of the most ancient houses in Portugal, was not one of the most noble, and he certainly had no claim to the distinguished rank he afterwards held, which he owed entirely to his uncle, brother Gaspard, a mere Portugueze gentleman; he himself being incapable of pushing his fortune, or aspiring to favour through his personal merit. His figure was greatly against him, for he was short, and far from handsome; add to this, he was ignorant, obstinate, deranged in his fortune, and capable of every crime; meanly servile towards Carvalho, whom he secretly detested; and so proudly vain of his birth, as openly to declare, that his family, being descended from _George_ (_the natural son of John the IId, surnamed the Great_) _he was but one degree removed from the crown_. Stung to the quick at being no longer treated with the same distinction as during the reign of John the Vth, he formed the terrible design of assassinating his successor; and his pride giving way to his resentment, he indiscriminately attached himself to every one who had, or who thought he had, reason to complain of the court; particularly to the Jesuits, and the family of Tavora. To the former he had always testified the greatest aversion during the administration of his uncle, brother Gaspard, but he now sought their society, frequently visiting them, and receiving them night and day in his own apartments. After some little time, he judged them worthy of his confidence, and revealed his shocking design to father Malagrida. The Jesuit having succeeded in bringing about a reconciliation between the duke and the Tavoras, who had long resented his having deprived them of several domains formerly belonging to their family, prevailed upon him to open his heart to the old marchioness de Tavora, whose confessor he was. The duke the more readily consented to this plan as he knew the implacable hatred borne by the marchioness to the king, and his minister, who had refused her solicitations in favour of her husband, for whom she wished to procure the title of duke. This lady was in every respect widely different from her brother-in law, the duke d'Aveiro. Nature had bestowed on her the most striking beauty, the most imposing carriage, and the most seductive graces. She was endowed with a genius capable of conceiving the most extensive plans, with judgment to ripen, and talents to execute them.