Again, other men sometimes used in their books expressions borrowed from Shakespeare or remarks which sound like allusions to something of his. Here, if we know the date of the other man's book, we learn that the play of Shakespeare from which he borrowed must have been in existence before that date. Thus, when the poet Barksted prints a poem in 1607 and borrows a passage in it from _Measure for Measure_, we conclude that _Measure for Measure_ must have been produced before 1607, or Barksted could not have copied from it. This form of evidence has its dangers, since occasionally we cannot tell whether Shakespeare borrowed from the other man or the other man from him; nevertheless it is often valuable. Furthermore, we sometimes find in contemporary books or papers, which are dated, an account of the acting of some play. A law student named John Manningham left a diary in which he records that on February 2, 1602 he saw a play called _Twelfth Night or What You Will_ in the Hall of the Middle Temple; and his account of the play shows that it was Shakespeare's. Dr. Simon Forman, in a similar diary, describes the performance of three Shakespearean plays, two of the accounts being dated. Still more important in this class is the famous allusion, already quoted, by Francis Meres in his _Palladis Tamia_, a {77} book published in 1598. In this he mentions with high praise six comedies of Shakespeare: _The Two Gentlemen of Verona_, _The Comedy of Errors_, _Love's Labour's Lost_, _Love's Labour's Won_,[1] _A Midsummer Night's Dream_, and _The Merchant of Venice_; and six "tragedies": _Richard II_, _Richard III_, _Henry IV_, _King John_, _Titus Andronicus_, and _Romeo and Juliet_.[2] Hence, we know that all these plays were written and acted somewhere before 1598, although three of them did not appear in print until 1623. The above list does not exhaust all the forms of external evidence, but merely shows its general nature. External evidence, as can be seen, is not something mysterious and peculiar, but simply an application of common sense to the problem in hand. Frequently two pieces of external evidence will accomplish what neither one could do alone. Often one fact will show that a play came somewhere before a certain date, but not show how long before, and another will prove that the play came after another date, without telling how long after. For example, _King Lear_ was written before 1606, for we have a definite statement that it was performed then. It was written after 1603, for it borrowed material from a book printed in that year. This method of hemming in a play between its earliest and its latest possible date is common and useful, both with Shakespeare and with other writers.