And he who grovels in the world of sense, and has only this uncertain perception of things, is not a philosopher, but a lover of opinion only...
The fifth book is the new beginning of the Republic, in which the community of property and of family are first maintained, and the transition is made to the kingdom of philosophers.

For both of these Plato, after his manner, has been preparing in some chance words of Book IV, which fall unperceived on the reader's mind, as they are supposed at first to have fallen on the ear of Glaucon and Adeimantus.

The 'paradoxes,' as Morgenstern terms them, of this book of the Republic will be reserved for another place; a few remarks on the style, and some explanations of difficulties, may be briefly added.
First, there is the image of the waves, which serves for a sort of scheme or plan of the book.

The first wave, the second wave, the third and greatest wave come rolling in, and we hear the roar of them.

All that can be said of the extravagance of Plato's proposals is anticipated by himself.