Thanks for your question Gudrun,
Thanks for your answer George,
George's explanation is GREAT!
I'd like to add one of small things.
The Grammar rule you just asked is, ---는 것,
Let's Break --는 것
First, Here, --"는" is sort of usage of "to verb" or "V+--ing".
For examples,
보다 "see" becomes 보 (verb-stem) + 는 = 보는 (seeing, to see)
하다 "do" becomes 하 (verb-stem) + 는 = 하는 (doing, to do)
먹다 "eat" becomes 먹 (verb-stem) + 는 = 먹는 (eating, to eat)
배우다 "learn" becomes 배우 (verb-stem) + 는 = 배우는 (learning, to learn)
Now you see HOW IMPORTANT TO KNOW 'VERB-STEM' for each verb in Korean!
Now, let's take a look at "것".
"것" is 'Possessive Pronoun' that attaches to 'adjective' or 'Verb + -ing' (most times) and help the phrase to become NOUN.
Remember this - in the sentence, A is B, A must be NOUN or Noun phrase.
For examples,
"Tim is a student" = 팀 ("Tim" - noun) + 이다 ("is" - verb) + 학생 ("a student" - noun)
therefore, "Tim is a student" becomes 팀은 학생이다 (I hope you know about the Topic-Marking Particle 은/는 already. IF NOT, please give a listen to Absolute Beginner Season 2 lesson 3 & 4)
"Seeing is believing" = 보는 ("seeing" - adjective) + 이다 ("is" - verb) + 믿는 ("believing" - adjective)
If I literally translate it, "Seeing is believing" becomes 보는 믿는 이다, which is NOT a Korean sentence at all.
HOWEVER, you can make it correct by attaching 것 right after 'Verb+ing' and, it becomes NOUN!!!
보는 "seeing" + 것 "possessive pronoun" = 보는 것 (FINALLY "seeing" becomes NOUN) in Korean.
Remember even in English, "seeing" can be both NOUN or ADJECTIVE itself.
in "Seeing is Believing", "seeing" is NOUN.
in "seeing boy is there", "seeing" is ADJECTIVE.
in Korean, you need to clearly make it sure about which is NOUN or which is ADJECTIVE.
Okay, I hope now you understood some of this grammar rule.
Okay, go back to "Seeing is believing" = (literal translation) is 보는 믿는 이다.
Now you know how to make 'Verb+ing' into NOUN by attaching 것.
"Seeing" 보는 + 것 "Possessive Pronoun" = 보는 것 "seeing (NOUN)"
"Believing" 믿는 + 것 = 믿는 것 "believing (NOUN)"
Finally, the correct translation for "seeing is believing" is 보는 것 + 은(Topic Marking Particle) 믿는 것 이다.
보는 것은 믿는 것이다. "seeing is believing"
"Doing is necessary" 하는 것은 필요하다.
"Eating is essential" 먹는 것은 필수적이다.
"Learning Korean is my dream" 한국어를 배우는 것은 + "learning Korean" 내 꿈 + "my dream" 이다 "is"
=한국어를 배우는 것은 내 꿈이다.
Same thing with "My dream is to learn Korean." = 내 꿈은 "my dream" + 한국어를 배우는 것 "learning Korean" + 이다 "is"
=내 꿈은 한국어를 배우는 것이다.
I think... I wrote too much (AGAIN!!!).
In order to explain this grammar rule correct, I have to explain or you have to already know about,
1.
Verb-stem - How to make 'verb' into 'adjective'
2.
Possessive Pronoun, 것 - what's the usage of 것
3.
Topic Marking Particles, (은/는) - why we need to attach these 은/는 right after SUBJECT
4.
Sentence Structure - in "A is B", A must be NOUN or NOUN phrase.
5.
Verb+ing + 것 - how to make 'Verb+ing' into NOUN by attaching 것.
I hope my explanation covers all of five above.
IF NOT, please give a listen to 'Absolute Beginner Season 2'. I made that season myself.
You will find that the season is so~~~ GREAT! EASY to understand.
cheers,
Tim