He felt one should not go through life as if everything was exchangeable.
他觉得做人不能朝三暮四反复无常。
But though labour be the real measure of the exchangeable value of all commodities, it is not that by which their value is commonly estimated. It is often difficult to ascertain the proportion between two different quantities of labour.
但是,尽管劳动是衡量所有商品交换价值的真正尺度,但并不是通常用来估计商品价值的尺度。通常很难确定两种不同劳动量之间的比例。