 In 1956 he was able to study the third draft of Locke's An Essay Concerning Human Understanding at the Pierpont Morgan Library, which resulted in a substantial addition to the second edition of John Locke, published in 1955.
<clarity>  In 1956 he was able to study the third draft of Locke's An Essay Concerning Human Understanding at the Pierpont Morgan Library, which resulted in a substantial addition to the second edition of John Locke, published in 1955.
 In 1956 he was able to study the third draft of Locke's An Essay Concerning Human Understanding at the Pierpont Morgan Library, which led to a substantial addition to the second edition of John Locke, published in 1955.