Assuming that pursuit of gains from monetary spending by economic agents is the driving force of money circulation in the social and economic system , and defining velocity of money circulation as the change in stock of money from its receiving to payment by economic agents influenced by gains from monetary spending , it then can be proved that velocity of circulation is a vector 摘要假定经济单位追求货币支出收益是货币在社会经济制度中流动的动力来源，把货币流通速度定义为经济单位在货币支出收益的作用下从收入到支出的时间内货币量的改变量；从该定义出发，可证明货币流通速度是一个有方向的矢量。
