== Sources == 

 In view of the fact that "thou" continues in use in parts of England, it would be nice to see a source to support this sentence: "Thou had almost gone out of usage entirely in most English dialects by the year 1650." 

 I would guess that in 1650, in the very early days of the expansion of English around the world, most English dialects were confined to England. If "thou" had almost gone out of usage in these dialects, it seems odd that the modern use of "thou" now only continues, apparently, in England, where it was virtually extinct 350 years earlier. Has its level of usage been unchanged (restricted mostly to Yorkshire) since 1650? Any clarification from reliable sources would be welcome.