君子之交淡如水。

The friendship between gentlemen is as pure as crystal; A hedge between keeps friendship green. (Zhuangzi)

君子之交淡如水，小人之交甘若醴；君之淡以亲，小人甘以绝。

Though light, the relationshio between superiro men is pure and long-lasting.  Though sweet, that between inferior men is eays to break.