 Kirk argues that Homeric poems differ from those traditions in their "metrical strictness", "formular system[s]", and creativity.In other words, Kirk argued that Homeric poems were recited under a system that gave the reciter much more freedom to choose words and passages to get to the same end than the Serbo-Croatian poet, who was merely "reproductive".Shortly thereafter, Eric Havelock's "Preface to Plato" revolutionized how scholars looked at Homeric epic by arguing not only that it was the product of an oral tradition, but also that the oral-formulas contained therein served as a way for ancient Greeks to preserve cultural knowledge across many different generations.