 But his philological concerns now were only a small part of a much larger project to make sense of the nature of the Greek culture itself . His work in this period shows a theoretical sophistication far beyond his earlier efforts , extending his theory of literacy toward a theory of culture itself . He said of the Dipylon inscription , a poetic line scratched into a vase and the earliest Greek writing known at the time , " Here in this casual act by an unknown hand there is announced a revolution which was destined to change the nature of human culture . " It is this larger point about the differences between oral and literate culture that represents Havelock 's most influential contribution . Walter J. Ong , for example , in assessing the significance of non @-@ oral communication in an oral culture , cites Havelock 's observation that scientific categories , which are necessary not only for the natural sciences but also for historical and philosophical analysis , depend on writing . These ideas were sketched out in Preface to Plato but became central to Havelock 's work from Prologue to Greek Literacy ( 1971 ) onward . 
