The gem cannot be polished ...

The gem cannot be polished without friction, nor man perfected without trials.
The gem cannot be polished without friction, nor man perfected without trials.
 Chinese Proverb

More phrases

We are in a survival mentality, and that's hard-wired into our humanity, because we are the winners of an evolutionary struggle of millions and millions and millions of years.
 John Shelby Spong
I've always come back from adversity, and I've always had the mentality of proving people wrong.
 David Beckham
I like to challenge hitters with a 'Here it is, hit it,' mentality. It's definitely a big part of my game, especially when I get in situations where I need it. I usually save a little bit so it's there for me.
 Justin Verlander
If a warrior is to succeed at anything, the success must come gently, with a great deal of effort but with no stress or obsession.
A warrior takes his lot, whatever it may be, and accepts it in ultimate humbleness. He accepts in humbleness what he is, not as a grounds for regret but as a living challenge.

Quotes from the same author

A single conversation across the table with a wise person is worth a month's study of books.
 Chinese proverb
A man who asks is a fool for five minutes. A man who never asks is a fool for life.
 Chinese proverb
The best time to plant a tree was 20 years ago. The second-best time is now.
 Chinese Proverb
The wise adapt themselves to circumstances, as water molds itself to the pitcher.
 Chinese Proverb