In many cases the 1st and/or third lines of verses have internal rhymes (mountain/fountain, November/remember etc). Is it too fanciful to guess that originally all these lines had internal rhymes? A couple of possibles are:

More sweeter it tasted than the gold he had wasted in place of It tasted more sweeter than the gold he had wasted

now united together like birds of one feather in place of now they are united like birds of one feather

Just a guess, I've no evidence to back it up.