Can you please help me pick out names for my new betas?

This will be #'s 3 & 4. (I know... I'm obsessed with decorating my apartment with fish!) My first two are named Plato and Aristotle. I can't figure out if I should go with the greek theme and name the other two Sophoclese and Homer, or should I go with the European philosopher thing and name them something like Locke and Voltaire?