A hallmark of Early Modern English is that it exhibits a lot of variance between the use of final -y and -ie. In the 16th century -ie is even found in Old English words, eg stonie. And Mulcaster in his Elementarie of 1582 effectively recommends the dominant use of -ie when he relegates final -y only to “sharp and loud” final vowels (eg, deny but prettie). Why did -ie become so widely used in the 16th century? Are there phonological reasons to select -ie over -y? Is it due to contemporary French practices? I assume it’s a complex mix of causes – if so, is there a study into the “rise and fall” of -ie?
Phonetically they are identical nowadays, but they probably were pronounced differently in the past. I know that, at one time, in French the pronunciation of -ie was different than -i, and still is in poetry (the -ie indicating the feminine form of a word). The ending -y is rarely ever found in French.