Three instances of the 은 particle in a row

Question

I'm having a hard time trying to guess the meaning of the third 은 in this sentence:

남산은 놉은 산은 아니지만 참 아름답습니다.

I know that this sentence means "Namsan is not a tall mountain, but it's really beautiful".

I know that the first 은 marks the subject. The second 은 is an adjectival suffix, needed when the adjective accompanies a noun within the same syntactic function. But I can't figure out what the third 은 means. It seems to mark the object of the verbal root 아니 ("not to be"). But, if I'm not mistaken, the idea of "(not) being sth" does not need a particle correlating that verb to its object.

Am I missing something?

Answer 1

아니다 does take a particle if what you're negating is a noun. That may be what's confusing you.

• Negating a noun (is not N) - use either 이/가 or 은/는 on the noun.

  • 나는 대학생이 아니다 = I am not a college student. (negative of 나는 대학생이다; X이다 <-> X이/가 아니다)
  • 나는 대학생은 아니다 = (I may be many things but) I am not a college student.
  • 이/가 sounds matter-of-fact and devoid of nuance, while 은/는 makes the negation more narrowly scoped as if some other thing is implied.

• Negating other verbs/adjectives (doesn't V, isn't A) - 1) use 지, 2) prefix the verb/adjective with the adverb 안/아니 (not. Nowadays 안 is predominant).

  • 내일은 학교에 가지 않는다. (present tense, verb)
  • 내일은 학교에 안 간다.
  • 어제는 학교에 가지 않았다. (past tense, verb)
  • 어제는 학교에 안 갔다.
  • 날씨가 덥지 않다. (present tense, adjective)
  • 날씨가 안 덥다.

높은 산은 아니지만 (놉은 -> 높은) in your example is one of the most common way of saying "is not a tall mountain but ...". 이 in place of 은 also works but it is not as natural in this sentence.

In some cases, the particle may be dropped, especially in day-to-day use, as in 난 바보 이니야 (= 난 바보가 아니야 = I'm not a fool).