Origin of a saying

[thesoothsayer]

Hi all,

I was just wondering where this saying originated from?
"qing1 chu1 yu4 lan4 er4 sheng1 yu4 lan4"

The common usage of qing1 nowadays seem to be green. However, I noticed that dictionaries list it as either blue or green. So, I was wondering if the qing1 in this saying means blue or green since I don't quite see the logic in saying that green comes from blue but is better than blue?
Thanks.

[kkcheng]

青 出 於 藍 勝 於 藍
qing1 chu1 yu4 lan4（ er4？？） sheng1 yu4 lan4"

or

青出於藍
ｃｈiｎｇ　ｃｈu　ｙu　laｎ　

藍，蓼藍，可以提取靛青染料的植物。青出於藍指青色是從蓼藍裡提煉出來的，但是顏色比蓼藍還深。

[Karolina]

What does 'qing chu yu lan er sheng yu lan' MEAN?

[Jetcheng Chu]

> What does 'qing chu yu lan er sheng yu lan' MEAN?

For example..., when students are better than their teacher, you can say 'qing1 chu1 yu2 lan2 er2 sheng4 yu2 lan2'.