Rhyme is therefore an indispensable element of French verse, and is vastly more important as a poetic ornament than it is in English; so important that Sainte-Beuve calls it the sole harmony (_l'unique harmonie_) of verse. Rhyme may be either masculine, when it involves but one syllable (_divinité: majesté_, _toi: roi_), or feminine, when it involves two syllables the second of which contains mute _e_ (_repose: rose_, _changées: ravagées_); and lines are called masculine or feminine according to their rhymes. Masculine rhymes must constantly alternate with feminine rhymes; that is, two masculine or feminine lines of different rhymes may never come together; but the younger poets have sought a greater liberty here as elsewhere, and poems with but one kind of rhyme occur (see p. 208). Rhyme to be perfect must satisfy the eye as well as the ear; masculine rhymes must have identity of vowel sound and the final consonants must be the same or such as would have the same sound if pronounced (_granit: nid_, _héros: bourreaux_; not _différent: tyran_); but silent consonants between the vowel and the final consonant do not count (_essaims: saints_, _corps: morts_). Feminine rhymes must have identity of rhyming vowels and of following consonant sounds if there be any; and the final consonants must be the same (_fidèles: citadelles_, _jolie: crie_; not _nuages: louage_). Variations from ordinary spelling are sometimes used to make words satisfy this rule of rhyming for the eye (_je vien_, _je voi_), but they are hardly approved. The ear seems even sometimes to play the subordinate rôle in the rhyme, for words are found in rhyme which satisfy the eye but not the ear (_Vénus: nus_). Rhyme as above described is called sufficient (_suffisante_); if it also involve identity of the consonant preceding the rhyming vowel (_consonne d'appui_) it is called rich (_riche_); (examples: _étoiles: toiles_, _bandit_; The French ear is unlike the English in considering _rime riche_ an additional beauty; the Romanticists especially have cultivated it, and there are whole poems where simply sufficient rhyme is the exception. A word may not rhyme with itself, but words identical in form but different in meaning may rhyme with each other (cf. first, fifth, and eleventh stanzas of _les Djinns_, p. 95. By the use of lines of different length and especially by the arrangement of the rhymes a great variety of stanza forms has been created, as well as certain definite forms for complete short compositions, known as fixed forms. The most common are the _ballade_, _rondel_, _rondeau_, and _triolet_, developed especially in the fourteenth and fifteenth centuries and revived in our own, and the sonnet, introduced from Italy during the Renaissance.