Earlier this week, I wrote about three things Shakespeare’s English gave him that our English no longer provides.

One of them was the coexistence of I know not and I do not know. This was a choice between competing grammatical constructions, but it had consequence for the poetic metre.

Think of the rhythm: I dó not knów fits differently into a line than I knów not or Í know nót.

The same kind of variation made it useful to have the two alternatives: knows and knoweth. The extra syllable of knoweth sometimes made all the difference in a line of iambic pentameter.