In the song "Danny Boy" we have: you must go and I must bide; but come ye back. Is there an actual difference in usage? Is it poetic license? I'd appreciate any illumination here.
Hi! 'Ye' is the old plural form of 'thou' , so it should really be, "... but come thou back." But this doesn't 'flow' in the same way! So it probably is poetic licence and also perhaps dialect usage.
'Ye' is generally used as a plural 'you' but in the song lyrics it appears to only refer to one person (Danny). In that respect it's both inconsistent and illogical, but this is a song we're referring to. As a side note, there is a type of ballad in traditional Irish music which is often referred to as a 'come-all-ye' (not hugely dissimilar to Bob Dylan's The Times They Are A Changin') which may have influenced the lyrics of this song.
"Ye" is the original second person plural nominative while "you" is the original objective case form of "ye"; so, it was originally Ye see me (Old English: Ge seoþ me(c)) and I see you (Old English: Ic seo eow(ic)) In early modern English the nominative "ye" was replaced by "you". In dialectal and poetic use the old form is still sometimes used. Maybe because "come ye" is a set phrase the old form is preserved here?
Ye, in addition to its plural meaning, was also "sed instead of thou in addressing a single person (originally as a mark of respect or deference, later generally...)" [OED]. The OED has many examples which demonstrate, over the course of four or five hundred years, the change from it being a mark of respect to its general use in respect to any person. The later examples seem to show preservation in dialect and regional speech rather wider usage.
