Over-production is not possible in all branches of industry at once, but it is possible in some as compared to others. - William Stanley Jevons

My principal work now lies in tracing out the exact nature and conditions of utility. It seems strange indeed that economists have not bestowed more minute attention on a subject which doubtless furnishes the true key to the problems of economics.

There are many portions of economical doctrine which appear to me as scientific in form as they are consonant with facts.

A spade may be made of any size, and if the same number of strokes be made in the hour, the requisite exertion will vary nearly as the cube of the length of the blade.