Let us consider, therefore, if Mill's argument is sound.

We shall find that it is vitiated by a fallacy which will, as soon as we have perceived it, show us the way to the truth of which we are now in search.

Let us begin with taking the argument as he himself applies it.
He brings it forward with special reference to agriculture, and aims it at the contention of a certain school of economists that nature in agriculture did more than in other industries.

To urge this, says Mill, is nonsense, for the simple reason that though nature in agriculture does something, it is impossible to determine whether the something is relatively much or little.

Let us, he says in effect, take the products of any farm, which we may for convenience' sake symbolise as so many loaves; and it is obviously absurd to inquire which produces most of them--the soil or the farm labourers.