What was the ‘Common Arrangement’? An Inquiry into John Stuart Mill's Boyhood Reading of Plato

This article is detective work, not philosophy. J. S. Mill's Autobiography records that at the age of seven he read, in Greek, ‘the first six dialogues (in the common arrangement) of Plato, from the Euthyphron to the Theaetetus inclusive’. Which were the other dialogues? On the arrangement common today, it would be Crito, Apology, Phaedo, Cratylus. On the arrangement common then, Theages and Erastai replace Cratylus, which makes seven dialogues. I show that this must be the answer by the evidence of James Mill's commonplace books and his writings on Plato. These reveal which collected edition of Plato he owned and which he would want to own. Conditions for studying Plato in the original were much harder than we are used to. The inquiry highlights both the ideological purity of the education James Mill designed for his son, and the difficulties he faced in realizing his plan.