One of the first and most difficult steps in a science is to conceive clearly the nature of the magnitudes about which we are arguing. - William Stanley Jevons

In this work I have attempted to treat economy as a calculus of pleasure and pain, and have sketched out,almost irrespective of previous opinions, the form which the science,as it seems to me, must ultimately take.

I feel quite unable to adopt the opinion that the moment goods pass into the possession of the consumer they cease altogether to have the attributes of capital.

Among minor alterations, I may mention the substitution for the name political economy of the single convenient term economics. I cannot help thinking that it would be well to discard, as quickly as possible, the old troublesome double-worded name of our science.