What is the difference between "selbst", "mich selbst", and "mir selbst"?

Question

As the title of this question says, what would be the difference between those three?

For example, I found this sentence:

Ich werde das Buch selbst behalten.

Why is it not

Ich werde das Buch mich selbst behalten

or

Ich werde das Buch mir selbst behalten?

Answer 1

The difference is in the case.

Rearrange the sentence and you'll get:

Ich selbst werde das Buch behalten.

This is the nominative case of the personal pronoun ich.

In the dative case you have:

Mir selbst ist es noch nicht passiert. (It didn't happen to me, yet)

and in the accusative case

Mich selbst betrifft es nicht. (It doesn't affect myself)

I can't think of a genitive sentence, however, if you use Selbst as a noun, you can use it in a more sophisticated style, like

Ich war nicht mehr Herr meiner Selbst (I was no longer in control of myself)