The fruit of labor is measurable, but how? In the enjoyment you get out if it? Okay. But if you’re not also the consumer, in the smile on the guy you sell it ti’s face. Yes, but that’s not very interesting to you. It is commonly measured in what you can exchange for it, through the medium of money. That is, prices.
But money has its own price. Because of variance amongst people in time preference—some save, others spend—supply of and demand fir it vary. It is silly for us to pretend like money is sterile and bears no fruit. There is a market for money just like there’s a market fir apples. The proof is that people are willing to buy it.
>> “The fruit of labor is measurable, but how?” <<
By literally measuring it. It may be board feet of lumber cut, feet of pipe trenched and laid, barrels filled with whatever, contracts reviewed, books written, but it is always measurable.
Money on the other hand is merely the method of exchange of that product. The ‘price’ of money relates only to acceleration of acquisition time for some product, tangible, abstract, or facilitative.