+Internal Evidence+.--By the above methods a few plays have been dated quite accurately, and many others confined between limits only two or three years {78} apart. But many plays are still dated very vaguely, and some are not dated at all. For further results we must fall back on internal evidence. The first, though by no means the most important, form of this consists of allusions _within the play to contemporary events_. If a boy should read in an old diary of his grandmother's that she had just heard of the fight at Gettysburg, he would feel certain that the words were written a few days after that great battle, even if there were no date anywhere in the manuscript. In the same way, when the Prologue of Shakespeare's _Henry V_ alludes to the fact that Elizabeth's general (the Earl of Essex) is in Ireland quelling a rebellion, we know that this was written between April and September of 1599, the period during which Essex actually was in Ireland. Similarly, certain details in _The Tempest_ appear to have been borrowed from accounts of the wreck of Sir George Somers's ship in 1609. As Shakespeare could not have borrowed from these accounts before they existed, he must have written his comedy sometime after 1609.[3] But the main form of internal evidence, what is usually meant by that term, is the testimony in the character and style of the plays themselves as to the maturity of the man who wrote them. Just as the stump of a tree sawn across shows its age by its successive rings of growth, so a poem, if carefully {79} examined, shows the rings of growth in the author's style of thought and expression. The simplest and most tangible form of this evidence is that which is found in meter. If we read in order of composition those plays which we have already succeeded in dating, we shall find certain habits of versification steadily growing on the author, as play succeeded play. In the first place, most of the lines in the early plays are 'end-stopped'; that is, the sense halts at the close of each line with a resulting pause in reading. In the later plays the sense frequently runs over from one line into another, producing what is called a 'run-on' line instead of an 'end-stopped' one. By comparing the following passages, the first of which contains nothing but end-stopped lines and the second several run-on lines, the reader can easily see the difference. (_a_) From an early play:-- "I from my mistress come to you in post: If I return, I shall be post indeed, For she will score your fault upon my pate. Methinks your maw, like mine, should be your clock, And strike you home without a messenger." --_Comedy of Errors_, I, ii, 63-67. (_b_) From a late play:-- "Mark your divorce, young sir, [end-stopped] Whom son I dare not call. Thou art too base [run-on] To be acknowledg'd. Thou, a sceptre's heir, [end-stopped] That thus affects a sheep-hook! Thou old traitor, [end-stopped] {80}