Suppose a person in an oral culture would undertake to think through a particular complex problem and would finally manage to articulate a solution which itself is relatively complex, consisting, let us say, of a few hundred words. How does he or she retain for later recall the verbalization so painstakingly elaborated? In the total absence of any writing, there is nothing outside the thinker, no text, to enable him or her to produce the same line of thought again or even to verify whether he or she has done so or not. Aides-memoire such as notched sticks or a series of carefully arranged objects will not of themselves retrieve a complicated series of assertions. How, in fact, could a lengthy, analytic solution ever be assembled in the first place? An interlocutor is virtually essential: it is hard to talk to yourself for hours on end. Sustained thought in an oral culture is tied to communication.
But even with a listener to stimulate and ground your thought, the bits and pieces of your thought cannot be preserved in jotted notes. How could you ever call back to mind what you had so laboriously worked out? The only answer is: Think memorable thoughts. In a primary oral culture, to solve effecttively the probem of retaining and retrieving carefully articulated thought, you have to do your thinking in mnemonic patterns, shaped for ready oral recurrence. Your thought must come into being in heavily rhythmic, balanced patterns, in repetitions or antitheses, in alliterations and assonances, in epithetic and other formulary expressions, in standard thematic settings (the assembly, the meal, the duel, the hero’s ‘helper’, and so on), in proverbs which are constantly heard by everyone so that they come to mind readily and which themselves are patterned for retention and ready recall, or in other mnemonic form. Serious thought is intertwined with memory systems. Mnemonic needs determine even syntax.
Walter J. Ong - Orality and Literacy: The Technologizing of the Word