Early page proofs of the first two signatures of Samuel Johnson's preface to his edition of The plays of William Shakespeare, published in 1765. This preface is regarded by many as one of Johnson's greatest works. The proof is annotated with many manuscript corrections in Johnson's hand. The corrections indicate that Johnson particularly wanted to eliminate verbal repetitions. A comparison with the published version reveals that this was not the final proof and that further alterations were made afterwards.
In 1756 Johnson had published proposals for printing his edition of Shakespeare's plays, however it was not until 1765, not long after meeting HLP for the first time, that the edition was published. It is almost certain that the preface was the last part of the edition to be written.
See Arthur Sherbo, The proof sheets of Dr Johnson's Preface to Shakespeare, Bulletin of the John Rylands Library, vol. 35 (1952), pp. 206-10.