If the book has an odd number of chapters, the middle of the book is easy to determine.
Machiavelli's "The Prince" contains an even number of chapters. Leo Strauss emphatically states the Preface is not a chapter. The middle of the 26 chapters would be chapters 13 and 14. Current authors use chapters and sometimes these are grouped into sections. If there are an odd number of sections,one needs to go the center of the section, the appropriate chapter, to find the authors true thoughts. Frequently, unpleasant truths are said by fools, the very young or the very old.
For texts that the author did not delineate chapters and verse (that is, they have been added by editors or through tradition), I can not offer absolute rules in this regard.
The Republic does not have the authors chapters or verses, but what is retained is the changing of the speakers. (For the complete text with the change of dialogue shown, go here.)
There are 30 (according to my count) changes in speakers. The middle of the 30 is the 15th and 16th dialogues.
This is the center of the dialogue changes, but represents, perhaps only the first 10 to 15 percent of the entire text. Therefore, in the example, counting words will not reveal the author's center.
The following example are exceprts from the 15th and 16th sections.
15 Adeimantus -SOCRATES
..I must confess that Glaucon has already said quite enough to lay me in the dust, and take from me the power of helping justice.
...Parents and tutors are always telling their sons and their wards that they are to be just; but why? Not for the sake of justice, but for the sake of character and reputation
... The universal voice of mankind is always declaring that justice and virtue are honourable, but grievous and toilsome; and that the pleasures of vice and injustice are easy of attainment, and are only censured by law and opinion
... they say that the gods apportion calamity and misery to many good men, and good and happiness to the wicked
... making an atonement for a man's own or his ancestor's sins by sacrifices or charms
... and are equally at the service of the living and the dead; the latter sort they call mysteries, and they redeem us from the pains of hell, but if we neglect them no one knows what awaits us.
... But if, though unjust, I acquire the reputation of justice, a heavenly life is promised to me. Since then, as philosophers prove, appearance tyrannizes over truth and is lord of happiness, to appearance I must devote myself
.... the concealment of wickedness is often difficult; to which I answer, Nothing great is easy.
... But what if there are no gods? or, suppose them to have no care of human things
... yet we know of them only from tradition and the genealogies of the poets;
... why then we had better be unjust, and offer of the fruits of injustice;
... and by our sinning and praying, and praying and sinning, the gods will be propitiated, and we shall not be punished.
... On what principle, then, shall we any longer choose justice rather than the worst injustice? when, if we only unite the latter with a deceitful regard to appearances, we shall fare to our mind both with gods and men, in life and after death, as the most numerous and the highest authorities tell us. Knowing all this, Socrates, how can a man who has any superiority of mind or person or rank or wealth, be willing to honour justice; or indeed to refrain from laughing when he hears justice praised?
... because he also knows that men are not just of their own free will;
... He only blames injustice who, owing to cowardice or age or some weakness, has not the power of being unjust. And this is proved by the fact that when he obtains the power, he immediately becomes unjust as far as he can be.
... --no one has ever blamed injustice or praised justice except with a view to the glories, honours, and benefits which flow from them.
... Had this been the universal strain, had you sought to persuade us of this from our youth upwards, we should not have been on the watch to keep one another from doing wrong, but every one would have been his own watchman, because afraid, if he did wrong, of harbouring in himself the greatest of evils.
... we shall say that you do not praise justice, but the appearance of it;
... and that you really agree with Thrasymachus in thinking that justice is another's good and the interest of the stronger, and that injustice is a man's own profit and interest, though injurious to the weaker.
Thrasymachus, the philosopher, is usually considered the mouth piece of Plato, but that view is not entirely correct, judging by the above.
We learn, through implication, that philosophy sees the gods as man made, the traditions of men and poets. Justice, it is implies, has no all encompassing or correct definition other than "Interest of the stronger". Since justice is not seen in Nature and, therefore not natural, there is no standard for this concept. This is demonstrated by Socrates when he refutes the conventional ideas of justice.
Nature shows that there is no equality, only hierarchy. The strong dominate the weak.
Nature is indifferent.
Nature is wasteful.
Everyone understands the concept-the interest of the stronger.
When I steal from a convenience store, justice is with me.
When I am caught stealing, justice is with the owner.
When I am in a police car, justice is with the officer.
When I am rescued by my followers, justice is with me.
When the SWAT team comes to my door, justice is with them.
When I am at trial, justice is with the court.
When I am in prison, justice is with the state.
When I escape from prison and go to Argentina, justice is with me.
In a Dictatorship, one man has justice.
In a Aristocracy, the elite have justice.
In a Republic, the land owners have justice.
In a Democracy, the masses have justice.