Homer is a legendary ancient Greek epic poet, traditionally said to be the author of the epic poems the Iliad and the Odyssey. The ancient Greeks generally believed that Homer was a historical individual, but modern scholars are skeptical: no reliable biographical information has been handed down from classical antiquity, and the poems themselves manifestly represent the culmination of many centuries of oral story-telling and a well-developed "formulaic" system of poetic composition. According to Martin West, "Homer" is "not the name of a historical poet, but a fictitious or constructed name." The poems are now widely regarded as the culmination of a long tradition of orally composed poetry, but the way in which they reached their final written form, and the role that an individual poet, or poets, played in this process is disputed. By the reckoning of scholars like Geoffrey Kirk, both poems were created by an individual genius who drew much of his material from various traditional stories. Others, like Martin West, hold that the epics were composed by a number of poets. Gregory Nagy maintains that the epics are not the creation of any individual; rather, they slowly evolved towards their final form over a period of centuries and, in this view, are the collective work of generations of poets. The date of Homer's existence was controversial in antiquity and is no less so today. Herodotus said that Homer lived 400 years before his own time, which would place him at about 850 BC; but other ancient sources gave dates much closer to the supposed time of the Trojan War. For modern scholarship, "the date of Homer" refers to the date of the poems' conception as much as to the lifetime of an individual. The scholarly consensus is that "the Iliad and the Odyssey date from the extreme end of the 9th century BC or from the 8th, the Iliad being anterior to the Odyssey, perhaps by some decades.",i.e. somewhat earlier than Hesiod, and that the Iliad is the oldest work of western literature. Over the past few decades, some scholars have been arguing for a 7th-century date. Those who believe that the Homeric poems developed gradually over a long period of time, however, generally give a later date for the poems: according to Nagy, they only became fixed texts in the 6th century. Alfred Heubeck states that the formative influence of the works of Homer in shaping and influencing the whole development of Greek culture was recognised by many Greeks themselves, who considered him to be their instructor.