Mrs Catherine, a most accomplished lady and celebrated writer, was the daughter of Captain David Trotter, a native of Scotland, and a naval commander in the reign of King Charles II. She was born in London on the 16th of August 1679, and baptized in the Protestant church, according to which she was bred up. She gave early marks of her genius; and learned to write, and also made herself mistress of the French language, by her own application and diligence, without any instructor; but she had some assistance in the study of the Latin grammar and logic, of which latter she drew up an abstract for her own use. The most serious and important subjects, and especially religion, soon engaged her attention. But notwithstanding her education, her intimacy with several families of distinction of the Roman Catholic persuasion exposed her, while very young, to impressions in favour of that church, which, not being removed by her conferences with some eminent and learned members of the church of England, she embraced the Roman Catholic communion, in which she continued till the year 1707. In 1695 she produced a tragedy called Agnes de Castro, which was acted at the theatre-royal when she was only in her seventeenth year. The reputation of this performance, and the verses which she addressed to Mr Congreve upon his Mourning Bride in 1697, were probably the foundation of her acquaintance with that celebrated writer. Her second tragedy, Fatal Friendship, was acted in 1698, at the new theatre in Lincoln's-Inn Fields. This tragedy met with great applause, and is still thought the most perfect of her dramatic performances. Her dramatic talents not being confined to tragedy, she brought upon the stage, in 1707, a comedy called Love at a Loss, or Most Vows carry it. In the same year she gave the public her third tragedy, entitled the Unhappy Penitent, acted at the theatre-royal in Drury Lane. But poetry and dramatic writing did not so far engross the thoughts of our author as to prevent her from sometimes turning them to subjects of a very different nature, and she distinguished herself in an extraordinary manner in defence of Mr Locke's writings, a female metaphysician being a remarkable phenomenon in the republic of letters.

She returned to the exercise of her dramatic genius in 1703, and fixed upon the revolution of Sweden, under Gustavus Ericson, for the subject of a tragedy. This tragedy was acted in 1706, at the queen's theatre in the Haymarket. In 1707 her doubts concerning the Roman Catholic religion, which she had so many years professed, having led her to a thorough examination of the grounds of it, by consulting the best books on both sides of the question, and advising with men of the best judgment, the result was a conviction of the falseness of the pretensions of that church, and a return to that of England, to which she adhered during the remainder of her life. In 1708 she was married to the Reverend Mr Cockburne, then curate of St Dunstan's, in Fleet Street, but who afterwards obtained the living of Long Horsely, near Morpeth, in Northumberland. He was a man of considerable abilities; and, among several things, wrote an account of the Mosaic Deluge, which met with some approbation from the learned. Mrs Cockburne's remarks upon some writers in the controversy concerning the foundation of moral duty and moral obligation were introduced to the world in August 1712, in the Literary Journal, entitled *The History of the Works of the Learned*. The strength, clearness, and vivacity shown in her remarks upon the most abstract and perplexed questions immediately raised the curiosity of all good judges about the concealed writer; and their admiration was greatly increased when her sex and advanced age were known. Dr Rutherford's *Essay on the Nature and Obligations of Virtue*, published in May 1744, soon engaged her thoughts; and notwithstanding the asthmatic disorder which had seized her many years before, and now left her small intervals of ease, she applied herself to the confutation of that elaborate discourse, and finished it with a spirit, elegance, and perspicuity, equal, if not superior, to the best of her former writings.

The loss of her husband in 1748, in the seventy-first year of his age, was a severe shock to her; and she did not long survive him, having died on the 11th of May 1749, in the seventy-first year of her age, after long supporting a painful disorder with that resignation to the Divine will which had been the governing principle of her life. Her works are collected into two large volumes 8vo, by Dr Birch, who has prefixed to them an account of her life and writings.