The consonants that precede the vowels where the rhyme begins, must be different in sound, and not the same; for then the rhyme will be too perfect; as light, delight; vice, advice, and the like; for though such rhymes were allowable in the days of Spenser and the other old poets, they are not so now, nor can there be any music in one single note. Cowley himself owns, that they ought not to be allowed except in Pindaric odes, which is a sort of free poetry, and there too very sparingly and not without a third rhyme to answer to both; as,
"In barren Age wild and inglorious lye,
And boast of past Fertility,
The poor relief of present Poverty."—Cowley.
Where the words fertility and poverty rhyme very well to the last word of the first verse, lye; but cannot rhyme to each other, because the consonants that precede the last vowels are the same, both in writing and sound.
But this is yet less allowable, if the accent be on the last syllable of the rhyme; as,
"Her Language melts Omnipotence, arrests
His hand, and thence the vengeful Light'ning wrests."—Blac.
From hence it follows, that a word cannot rhyme to itself though the signification be different; as, he leaves to the leaves, &c.
Nor the words that differ both in writing and sense, if they have the same sound, as maid and made, prey and pray, to bow and a bough; as,