  While Catharine Trotter was establishing her reputation as a playwright, she was also studying Locke’s work, An Essay Concerning Human Understanding. Trotter was so deeply impressed with his ideas that she felt obliged to take up her pen in defense of Locke against one critic in particular. This critic was the posthumously-identified Thomas Burnet, who, beginning in 1697, wrote three pamphlets in criticism of Locke’s Essay. Cockburn’s first philosophical work was a response to Burnet. Entitled The Defence of Mr. Locke’s Essay of Human Understanding, Cockburn’s work was published in 1702. Locke himself was so impressed with the work, he presented Cockburn with a substantial gift of money and books in appreciation.