《论衡·卷九·问孔篇》
配合感情要赠送礼物，动了感情，礼物就要随着送去。礼物与感情要相称，君子都是这样做的。
副情而行礼，情起而恩动，礼情相应，君子行之。
Gifts should be given in line with your emotions, when emotions are stirred, gifts should be given accordingly. The gift and the emotions should match, gentlemen all do this.