It was in the metrical treatment that Ennius's greatest achievement lay. For the first time in any consecutive way he introduced the hexameter into Latin poetry. It is true that Plautus had composed his epitaph in that measure, if we may trust Varro's judgment on its genuineness. [4] And the Marcian oracles, though their rhythm has been disputed, were in all probability written in the same. [5] But these last were translations, and were in no sense an epoch in literature. Ennius compelled the intractable forms of Latin speech to accommodate themselves to the dactylic rhythm. Difficulties of two kinds met him, those of accent and those of quantity. The former had been partially surmounted by the comic writers, and it only required a careful extension of their method to render the deviations from the familiar emphasis of daily life harmonious and acceptable. In respect of quantity the problem was more complex. Plautus had disregarded it in numerous instances (_e.g. dari_), and in others had been content to recognize the natural length or shortness of a vowel (_e.g. senex ipse_), neglecting the subordinate laws of position, &c. This custom had, as far as we know, guided Ennius himself in his dramatic poems; but for the epos he adopted a different principle. Taking advantage of the tendency to shorten final vowels, he fixed almost every doubtful case as short, _e.g. musa, patre, dare, omnibus, amaveris, pater_, only leaving the long syllable where the metre required it, as _condiderit_. By this means he gave a dactylic direction to Latin prosody which it afterwards, though only slightly, extended. At the same time he observed carefully the Greek laws of position and the doubled letters. He admitted hiatus, but not to any great extent, and chiefly in the caesura. The lengthening of a short vowel by the ictus occurs occasionally in his verses, but almost always in words where it was originally by nature long. In such words the lengthening may take place even in the thesis of the foot, as in-- "non enim rumores ponebat ante salutem." Elision played a prominent part in his system. This was natural, since with all his changes many long or intractable terminations remained, _e.g. enim, quidem, omnium_, &c. These were generally elided, sometimes shortened as in the line quoted, sometimes lengthened as in the comedians,-- "inimicitiam agitantes."