Abierto tiene delante
Aquel cajón singulàr
Hábilmente preparado,
Que, mitad cuna y mitàd
Barco, condujo en su seno
Al desdichado rapàz.
(2) words accented on the last syllable (agudos) cannot assonate with those accented on the penult (graves), on the antepenult (esdrújulos), or on any preceding syllable (sobresdrújulos).
(3) the assonance is of two vowels and no more in words accented on the penult (graves), on the antepenult (esdrújulos), or any preceding syllable (sobresdrújulos); cf. the assonance in ù—o in mùstio—fúlgido—púsoselo.
Penults may assonate arbitrarily with antepenults, but the effect is better when penults assonate with penults and antepenults with antepenults. But little use is made in rhyme of words accented on a syllable preceding the antepenult.
In the final unaccented syllable, as the result of an obscured pronunciation, i and u, if not in diphthongs, assonate as e and o respectively, e.g., cáliz—vàlle, débil—vèrde, Vènus—cièlo, espíritu—efímero. Possible assonances are, then, those in á, é, í, ó, ú (a difficult one), à—a, à—e, à—o, è—a, è—e, è—o, ì—a, ì—e, ì—o, ò—a, ò—e, ò—o, ù—a, ù—e, ù—o.