Help on a specific usage of こそ


> 好きこそものの上手なれ。 We tend to be good at those things we like. / People become
> best at what they love the most.

How does the こそ work here? Is this use of こそ common outside of proverbs?




_Edit in revision 4: If you are interested in this proverb, do not miss
the[answer by Matt](https://japanese.stackexchange.com/a/4593/15) to another
question, where he cites an earlier form of the proverb._

_Edit in revision 2: I rewrote the answer completely to give a more detailed
explanation. If you prefer a shorter answer, see the[old
revision](https://japanese.stackexchange.com/revisions/4482/1)._

こそ signifies emphasis. In other words, it adds the meaning of exclusiveness
(as sawa wrote in a comment to this answer). It is not archaic, and it is
common to see こそ outside of proverbs or set phrases (see Paul Richter’s answer
for examples). In this answer, I will try to explain 好きこそものの上手なれ, focusing on
the role of こそ.

Without こそ, the sentence would be

> 好きはものの上手なり。 Liking makes mastery.

好き means the action of liking something, just as in modern Japanese.
[ものの[上手]{じょうず}](http://dic.yahoo.co.jp/dsearch?p=%E7%89%A9%E3%81%AE%E4%B8%8A%E6%89%8B&stype=1&dtype=0&dname=0ss)
is an archaic phrase which means a person who is very skilled at something. なり
is a copula in classical Japanese. Therefore the literal meaning of the
sentence above is roughly “Liking = A very skilled person,” but obviously this
does not make sense because an action is not a person. I think that it means
“Liking makes a very skilled person,” or in short, “Liking makes mastery,” but
I do not know the exact reason this “action = person” construct can be used.

Now we add こそ and the sentence becomes

> 好き **こそ** ものの上手なれ。 _It is_ liking _that_ makes mastery.

好きこそ means “liking, and nothing else.” So the sentence means that liking and
not anything else (such as aptitude) makes mastery. A similar meaning can be
expressed in English using a [cleft
sentence](http://en.wikipedia.org/wiki/Cleft_sentence) “It is … that …” like
the sentence above.

I changed the auxiliary verb なり at the end of sentence to なれ when I added こそ.
As Chocolate pointed out in a comment, this is an instance of the grammatical
phenomenon called 係り結び. In classical Japanese, when a phrase/clause ending
with particle こそ modifies a conjugating word at the end of a sentence, that
conjugating word takes 已然形 instead of 終止形. Similarly, when a phrase/clause
ending with one of particles ぞ, なむ, や, and か modifies a conjugating word at
the end of a sentence, that conjugating word takes 連体形. This phenomenon is
called 係り結び.




_Edit in revision 4: If you are interested in this proverb, do not miss
the[answer by Matt](https://japanese.stackexchange.com/a/4593/15) to another
question, where he cites an earlier form of the proverb._

_Edit in revision 2: I rewrote the answer completely to give a more detailed
explanation. If you prefer a shorter answer, see the[old
revision](https://japanese.stackexchange.com/revisions/4482/1)._

こそ signifies emphasis. In other words, it adds the meaning of exclusiveness
(as sawa wrote in a comment to this answer). It is not archaic, and it is
common to see こそ outside of proverbs or set phrases (see Paul Richter’s answer
for examples). In this answer, I will try to explain 好きこそものの上手なれ, focusing on
the role of こそ.

Without こそ, the sentence would be

> 好きはものの上手なり。 Liking makes mastery.

好き means the action of liking something, just as in modern Japanese.
[ものの[上手]{じょうず}](http://dic.yahoo.co.jp/dsearch?p=%E7%89%A9%E3%81%AE%E4%B8%8A%E6%89%8B&stype=1&dtype=0&dname=0ss)
is an archaic phrase which means a person who is very skilled at something. なり
is a copula in classical Japanese. Therefore the literal meaning of the
sentence above is roughly “Liking = A very skilled person,” but obviously this
does not make sense because an action is not a person. I think that it means
“Liking makes a very skilled person,” or in short, “Liking makes mastery,” but
I do not know the exact reason this “action = person” construct can be used.

Now we add こそ and the sentence becomes

> 好き **こそ** ものの上手なれ。 _It is_ liking _that_ makes mastery.

好きこそ means “liking, and nothing else.” So the sentence means that liking and
not anything else (such as aptitude) makes mastery. A similar meaning can be
expressed in English using a [cleft
sentence](http://en.wikipedia.org/wiki/Cleft_sentence) “It is … that …” like
the sentence above.

I changed the auxiliary verb なり at the end of sentence to なれ when I added こそ.
As Chocolate pointed out in a comment, this is an instance of the grammatical
phenomenon called 係り結び. In classical Japanese, when a phrase/clause ending
with particle こそ modifies a conjugating word at the end of a sentence, that
conjugating word takes 已然形 instead of 終止形. Similarly, when a phrase/clause
ending with one of particles ぞ, なむ, や, and か modifies a conjugating word at
the end of a sentence, that conjugating word takes 連体形. This phenomenon is
called 係り結び.

