It was Benfey who, as on so many other points, so on the accent of vocatives, was the first to point out (in 1845) that it was a fundamental law of the Aryan language to place the acute on the first syllable of all vocatives, both in the singular, and in the dual and plural.[9] In Sanskrit this law admits of no exception; in Greek and Latin the rhythmic accent has prevailed to that extent that we only find a few traces left of the original Aryan accentuation. It is well known that in vocatives of nouns ending in _ius_, the ancient Romans preserved the accent on the first syllable, that they said _Vírgili_, _Váleri_, from _Virgílius_ and _Valérius_. This statement of Nigidius Figulus, preserved by Gellius, though with the remark that in his time no one would say so, is the only evidence of the former existence of the Aryan law of accentuation in Latin. In Greek the evidence is more considerable, but the vocatives with the accent on the first syllable are, by the supreme law of the rhythmic accent in Greek, reduced to vocatives, drawing back their accent as far as they can, consistently with the law which restricts the accent to the last three syllables. Thus while in Sanskrit a word like Ἀγαμέμνων would in the vocative retract the accent on the first syllable Ἄγαμεμνον, the Greek could do no more than say Ἀγάμεμνον with the accent on the antepenultimate. In the same manner the vocative of Ἀριστοτέλης, can only be Ἀριστότελες, whereas in Sanskrit it would have been Ἄριστοτελες. Here, however, the question arises, whether in words like Ἀγαμέμνων[10] and Ἀριστοτέλης[11] the accent was not originally on the antepenultimate, but drawn on the penultimate by the rhythmic law. This is certainly the case in ἥδιον, as the vocative of ἡδίων, for we know that both in Sanskrit and Greek, comparatives in ιων retract their accent as far as possible, and have it always on the first syllable in Sanskrit, always on the penultimate in Greek, if the last syllable is long. But, _cessante causâ cessat effectus_, and therefore the accent goes back on the antepenultimate, not only in the vocative, but likewise in the nom. neuter ἥδιον. It is possible that the same process may explain the vocative δέσποτα from δεσπότης, if we compare Sanskrit compounds with +pati+, such as +dâsápati+, +gấspati+, +dámpati+, which leave the accent on the first member of the compound. In Δημήτηρ also all becomes regular, if we admit the original accentuation to have been Δήμητηρ, changed in Δημήτηρ, but preserved in the genitive Δήμητρος, and the vocative Δήμητερ.[12]