We are not therefore surprized to find that Plato himself has nowhere clearly explained his doctrine of ideas; or that his school in a later generation, like his contemporaries Glaucon and Adeimantus, were unable to follow him in this region of speculation.

In the Sophist, where he is refuting the scepticism which maintained either that there was no such thing as predication, or that all might be predicated of all, he arrives at the conclusion that some ideas combine with some, but not all with all.

But he makes only one or two steps forward on this path; he nowhere attains to any connected system of ideas, or even to a knowledge of the most elementary relations of the sciences to one another.
BOOK V.I was going to enumerate the four forms of vice or decline in states, when Polemarchus--he was sitting a little farther from me than Adeimantus--taking him by the coat and leaning towards him, said something in an undertone, of which I only caught the words, 'Shall we let him off ?' 'Certainly not,' said Adeimantus, raising his voice.

Whom, I said, are you not going to let off?
'You,' he said.

Why?
'Because we think that you are not dealing fairly with us in omitting women and children, of whom you have slily disposed under the general formula that friends have all things in common.' And was I not right?
'Yes,' he replied, 'but there are many sorts of communism or community, and we want to know which of them is right.