Use of prepositions "от" and "из" for indicating a cause in Genitive case

Question

As far as I know, you use Genitive case when indicating the cause of something and that can be with either "от", "из" or "из-за".

You use "от" when the cause is a physical or psychological change

от страха, от радости

You use "из" for feelings, inciting positiveness

из вежливости, из любви

So I am having trouble understanding why the following prepositions are used in the following examples:

Он плакал от счастья.
Она сделала это из любви.

To me it seems that in the first sentence "из" should be used as "счастья" or "happiness" is a positive emotion, while in the second sentence "от" should be used, as it indicates she did something "because of", without it indicating she did something positive.

Answer 1

The difference between "из" and "от" is the following:

When you have some circumstances and make a decision based on them, you are to say "из".
But when you don't make any decisions, you just have circumstances that determine your behavior, use "от".

For example, "он делал это из страха перед наказанием" means that he knew that otherwise he would be punished, and that's why he decided to do it. But "он дрожал от страха" doesn't mean that he knew, that he was frightened, and that's why he decided to tremble. No, he didn't make such decision, he just was trembling in fear.

Answer 2

You use "от" when the cause is a physical or psychological change

You use "из" for feelings, inciting positiveness

That's not quite correct.

От means an emotion causes you do something, probably as a reflex, against your will:

• Захлебнувшись от возмущения, она дойдёт до двери, закроет её, закроет все двери.

• Вы ей ещё дата-кабель купите к телефону, она под потолком парить от счастья будет.

• Люди сжимаются от страха, как только слышат о принятии очередных законов, потому что они, как правило, против улучшения жизни.

In English this is usually conveyed using "to make smb. do smth.": "fear makes people cringe", "she'll be so happy it will make her fly" etc.

Из means emotion or feeling affects your decision to do something willingly. It does not have to be a positive emotion, you can use из чувства вины, из боязни etc:

• Спросит из вежливости: "Ну, как у вас там?" ― а ответа уже не слушает.

• Они должны интересоваться наукой хотя бы из чувства самосохранения.

• Но ни потерпевшие, ни свидетели не явились на процесс. Из боязни.

In English this is usually out of smth.: "he'll ask out of courtesy", "they did not attend out of terror" etc.

Он плакал от счастья

Here, sense of happiness made him cry, though probably he did not want to.

Она сделала это из любви.

Here, she was in love, and the sense of love made her feel like doing this, at her own will.

Answer 3

ОТ + genitive denotes physical and emotional (involuntary) cause :

умереть от рака(to die from cancer), замереть от восторга (to freeze in excitement) , побледнеть от страха (to pale in fear)

ИЗ + genitive means that emotional cause motivates a deliberate action:

убить из ревности (to kill out of jealousy ), соврать из страха (to lie out of fear)