The rules of Irish verse have nothing in common with classical Latin metres, which were based on the combination of short and long syllables. In Low-Latin, indeed, we find occasionally alliteration, rhyme, and a fixed number of syllables, but these novelties are obviously of foreign origin, and date from the time when the Romans borrowed them from the nations which they called barbarous. We cannot prove beyond yea or nay that they are of Celtic origin, but it is extremely probable that they are, for it is among the Celts both of Ireland and of Wales that the harmonizing of vowels and of consonants has been carried to the highest degree of perfection. This learned art was not acquired without long study. The training of a poet (_filé_) lasted twelve years, or more. The poets had a regular hierarchy. The highest in rank, the _ollamh_, knew 350 kinds of verse and could recite 250 principal and 100 secondary stories. The _ollamhs_ lived at the court of the kings and the nobles, who granted them freehold lands; their persons and their property were sacred; and they had established in Ireland schools in which the people might learn history, poetry, and law. The bards formed a numerous class, of a rank inferior to the _filé_; they did not enjoy the same honors and privileges; some of them even were slaves; according to their standing, different kinds of verse were assigned to them as a monopoly. The Danish invasions in the ninth century set back for some time the development of Irish poetry, but, when the Irish had driven the fierce and aggressive sea-rovers from their country, there was a literary renascence. This was in turn checked by the Anglo-Norman invasion in the twelfth century, and thereafter the art of versification was no longer so refined as it had formerly been. Nevertheless, the bardic schools still existed in the seventeenth century, more than four hundred years after the landing of Strongbow, and, in them, students followed the lectures of the _ollamhs_ for six months each year, or until the coming of spring, exercising both their talents for composition and their memory. A catalogue of Irish poets, which has recently been made out, shows that there were more than a thousand of them. We have lost many of the oldest poems, but the Irish scribes often modernized the texts which they were copying. Hence the language is not always a sufficient indication of date, and it is possible that, under a comparatively modern form, some very ancient pieces may have been preserved. Even if the poems attributed to Amergin do not go back to the tenth century B.C., as has been claimed for them, they are in any case old enough to be archaic, and certain poems of the mythological cycle are undoubtedly anterior to the Christian era.