Plato is from the classical period in Greece and, well let's face it, forms much of the consciousness that we all, as societies experience today. Without Socratic followers, without Aristotle's teachings and formulation of influence within the earshot of Alexander the Great, the infectious nature of Western thought would not have come into being in quite the same way.
Plato's life and death begin approximately 425 years BCE with more than three hundred years before the coalescence of influences we attribute to Virgil. The landscape in Virgil's lifetime is one of strife and political change. The fall of the Roman Republic and subsequent transition into the Roman Empire resonates throughout much of Virgil's work. From the Eclogues to the Georgics and even the epic Aeneid we see (blah, blah...).