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

The whole result of continued labour is not often consumed and enjoyed in a moment; the result generally lasts for a certain length of time. We must then conceive the capital as being progressively uninvested.

Repeated reflection and inquiry have led me to the somewhat novel opinion, that value depends entirely upon utility.

Aristotle's dictim... may then be formulated somewhat as follows:—Whatever is known of a term may be stated of its equal or equivalent. Or, in other words, Whatever is true of a thing is true of its like. ...the value of the formula must be judged by its results; ...it not only brings into harmony all the branches of logical doctrine, but... unites them in close analogy to the corresponding parts of mathematical method. All acts of mathematical reasoning may... be considered but as applications of a corresponding axiom of quantity...