It appears that there were two broad developments in Plato's literary style: an earlier one which was slow and gradual and a later, starting when he was about sixty, which was sudden and rapid. Regarding the former, where the changes concerned his vocabulary and were for the most part probably unconscious, one would expect the trend to be uneven and at times haphazard; in the latter, which concerned the euphony of his prose and involved a deliberate choice in respect of hiatus avoidance and rhythm, a more rational and systematic evolution might be anticipated, with any aberrations in it explicable by known or deducible factors.

The early research on Plato's vocabulary by Campbell, Dittenberger and Schanz, culminating in Ritter's book on the subject, identified in Soph., Pol., Phil., Tim., Crit. and Laws a group of dialogues which were distinguished from the rest by an exclusive or increased occurrence in them of certain words and phrases. Subsequent investigations into this aspect of style arrived at the same conclusion, and the dichotomy was confirmed by two further criteria with the discovery that only in these works, together with the Epin. and Epist. vn, did Plato make a consistent attempt to avoid certain types of hiatus and achieve a different kind of prose rhythm.

It has been argued that Plato avoided hiatus changeably rather than consistently after a certain date. This is to attribute to an elderly philosopher the disposition of a young woman pleased with a new hat, who then tires of it and lays it aside, only to rediscover its charm after a brief passage of time.