It is often said that to understand Plato we must understand his times. Many readers who might accept without question this saying of historical criticism may still wonder why we should think it necessary to begin our enquiry as far back as Homer and beyond. In the case of Plato there is an even greater need to pursue the argument back to the very beginnings of the historical period in which he lived and worked.

It is quite impossible to understand the genesis of Plato's ideas without understanding the profound change that Greek society underwent in the post-Homeric period that...