SHAKESPEARE DID NOT WRITE IN OLD ENGLISH. The declared purpose of the translation of Sonnet 18 into Old English was to make the point that Shakespeare did not write in Old English. Shakespeare wrote in Early Modern English. This article by Amanda Mabillard on the Shakespeareonline site gives good examples of Old English (from Beowulf) and Middle English (from Chaucer’s Canterbury Tales). Amanda Mabillard ways that: “By about 1450, Middle English was replaced with Early Modern English, the language of Shakespeare, which is almost identical to contemporary English.”
I posted here on the contention by the linguist John McWhorter that for a modern audience “the English of 1600, when Shakespeare was writing, “has changed not only in terms of a few exotic vocabulary items, but in the very meaning of thousands of basic words and in scores of fundamental sentence structures.” He thinks the cutoff date for when the English language became the language we use is 1700, and, as I said in the post, he persuaded me.