Learn Hardcore Russian: Учёный нашёл источник реки в горах. - The scientist found the source of the river in the mountains.

Although учёный can function as an adjective meaning “learned,” in this sentence it’s a noun meaning “scientist.” You can tell because it’s the subject (the one doing the action), and it appears in the nominative case (no ending change from its dictionary form).

Why is нашёл spelled with ё, and how is it pronounced?

In Russian, the letter ё always represents the sound [o] with the stress on that syllable. So нашёл is pronounced [nɐˈʂol], with the stress on -шёл. The ё tells you both the sound and that this is the past tense, masculine singular form of найти (“to find”).

Why is источник in the accusative case, and how can I recognize that?

Источник is the direct object of нашёл (he found what?), so it takes the accusative case. Since источник is an inanimate masculine noun ending in a consonant, its nominative and accusative forms look identical. You identify the accusative here because it answers “what?” and follows the verb.

Why is реки in the genitive case?

Реки is the genitive singular of река (“river”). It answers the question “whose source?” or “source of what?” In Russian, when you say “source of the river,” the word “river” goes into the genitive.

Why aren’t there words for “a,” “an,” or “the” in this sentence?

Russian does not have articles like “a,” “an,” or “the.” Definiteness or indefiniteness is inferred from context, word order, or additional words (e.g., “этот учёный” for “this scientist”), but no separate article word is needed.

Why is it в горах (prepositional plural) instead of another case?

When indicating location (“in the mountains”), Russian uses the preposition в plus the prepositional case. The noun горы (“mountains”) takes the prepositional plural form горах to agree with в.

Could I say на горах instead of в горах?

Not for a general location “in the mountains.” На горах would emphasize “on top of the peaks,” as if you’re on the summits themselves. To speak of being or finding something somewhere within a mountain range, you always say в горах.

Can I rearrange the word order in this sentence?

Yes. Russian has relatively flexible word order. All these are valid: • Учёный нашёл источник реки в горах. (neutral S-V-O)
• В горах учёный нашёл источник реки. (emphasizes “in the mountains”)
• Источник реки учёный нашёл в горах. (stresses “the river’s source”)
The cases (nominative, accusative, genitive, prepositional) keep the roles clear despite the order.

What’s the difference between источник, исток, and родник?

• Источник literally means “source” or “spring” and can refer to any water source.
• Родник specifically means a natural spring where water bubbles up from the ground.
• Исток refers to the starting point of a river, not necessarily a visible spring.
In “учёный нашёл источник реки,” you highlight the water spring where the river begins.