When talking about why something happened, Russian makes a distinction between an involuntary physical reaction and a conscious, deliberate motive. Both situations require the Genitive case, but they use different prepositions: от and из.
Involuntary Causes (от + Genitive)
Use the preposition от (from) to express an involuntary, physical, or overwhelming emotional cause. This is for reactions the subject cannot control, such as shivering from cold or falling asleep from fatigue.
To form the Genitive case:
- Masculine nouns ending in a consonant add -а (like страх → страха and холод → холода).
- Feminine nouns ending in -а change to -и (like скука → скуки).
- Feminine nouns ending in a soft sign (-ь) change to -и (like усталость → усталости).
Conscious Motives (из + Genitive)
Use the preposition из (often meaning "out of") when an action is deliberate, driven by a conscious motive, social grace, or internal trait. You use из when the person chooses to act based on feelings like curiosity, politeness, pity, or principle.
For neuter nouns ending in -о, the Genitive ending is -а (like любопытство → любопытства).
Comparing the Two
The distinction is entirely about control. You act из (out of) a conscious motive, but you suffer от (from) a physical or emotional state that overpowers you. Notice how both are used in the following sentence:
