The door opened of itself.

Question

The doors opened of themselves.
The doors opened of itself.

(Which one is incorrect above?)

He went to the movies of himself.
= He went to the movies alone.
(They have the same meaning, don't they?)

He solved the problem for himself.
= He solved the problem withour others' help.
= He solved the problem without anothers help.

(Are they all the same?)

1. The boy is good in itself.
2. The boy is good in himself.
3. Nature is good in itself.

Which do I have to use, 'itself' or 'himself'?

Answer 1

In the first set, replace "of" with "by" if you need a preposition at all. In the 2nd set, you do not want "of" in the first sentence. Either He went to the movies himself. OR He went to the movies by himself. Plus: He went to the movies alone. Yes, they essentially say the same thing.

In the 3rd set: Are they exactly the same, no. He solved the problem without (spelling error) others' help. = others is plural with the phypen where it is. OR He solved the problem without another's help. = singular but requiring the hyphen.

Set 4: The boy is good in himself. Nataur is good in itself.

Sra

P.S. The girl is good in herself.

Answer 2

None of the doors opened are correct usage. You may say -
The door opened by itself.
The doors opened by themselves.

We would not say "of himself".
He went by himself and he went alone - both mean the same thing.

Again, by himself - instead of - for himself
Others would not have an apostrophe.

Yes, they are all correct.

In the last group, in itself would never be used in reference to a boy.
In fact, one would never use "in himself" either.

The boy is good - is suffient
Or you can say - The boy is good; he doesn't need the help of others.