Arising from an expenditure of human force in general, samples of the same indiscriminate work, goods reveal only that in your production has been spent a work force. In other words: they work has accumulated. Goods are values in both that are embodiment of that work, without analyzing its shape. What is observed in common in the relationship of change or the change of the goods value is its value, and that we will try next. MAGNITUDE OF THE VALUE, SOCIALLY NECESSARY LABOUR TIME. From the above analysis we can now say that the substance of value is labour.

The measure of the amount of the value is the amount of work, which in turn is measured by the length, either by the working time. Working time that determines the value of a product is the time socially necessary to produce it, or better, the time needed, not in a particular case, but considered as term medium, i.e., the time requiring a work performed according the average degree of skill and intensity under the ordinary conditions regarding the agreed social environment. The magnitude of the value of a commodity would not suffer alteration if the time necessary to produce it It remained the same; but it varies everytime amending the labor productivity, i.e. with each alteration that is inserted into the activity of the procedures or external conditions in which the labour force is manifested. Productivity because of work, depends among other things, the ability to average workers, the breadth and effectiveness of media produce and exclusively natural circumstances; for example, the same amount of work is represented in a porcelain lamp simple if the conditions have been favorable and average lamp otherwise. Generally speaking, if the labor productivity increasing, decreasing the time required for the production of an article, this article value decreases and conversely, if productivity decreases, the value increases.