The diction also of Roman poetry betrays many traces of imitation. Some of the early Latin tragedies were literal translations from the works of the Athenian dramatists; and fragments of the rude Roman copy may still be compared with the polished expression of the original. Some familiar passages of the Iliad may be traced among the rough-hewn fragments of the Annals of Ennius. Even Lucretius, whose diction, more than that of most poets, produces the impression of being the immediate creation of his own mind, has described outward objects, and clothed his thoughts, in language borrowed from Homer, Empedocles, and Euripides. The short volume of Catullus contains translations from Sappho and Callimachus, and frequent imitations of other Greek poets; and, from the extant fragments of Alcaeus, Anacreon, and others of the Greek lyric poets, it may be seen how frequently Horace availed himself of some turn of their expression to invest his own experience with old poetic associations. Virgil, whose great success is, in no slight measure, due to the skill and taste with which he used the materials of earlier Greek and native writers, has reproduced the heroic tones of Homer in his epic, and the mellow cadences of Theocritus in his pastoral poems; and has blended something of the antique quaintness and oracular sanctity of Hesiod with the golden perfection of his Georgics. But besides the direct debt which each Roman poet owed to the Greek author or authors whom he imitated, it is difficult to estimate the extent to which the taste of the later Romans was formed by the familiar study of Greek literature. The habitual study of any foreign language has an influence not on style only, but even on the structure of thought and the development of emotion. The Roman poets first learned, from the study of Greek poetry, to feel the graceful combinations and the musical power of expression, and were thus stimulated and trained to elicit similar effects from their native language. It is for this gift, or power over language, that Lucretius prays in his invocation to the creative power of Nature,-- Quo magis aeternum da dictis, diva, leporem;