It is common to distinguish necessaries, comforts, and luxuries; the first class including all things required to meet wants which must be satisfied, while the latter consist of things that meet wants of a less urgent character.

Though a simple book can be written on selected topics, the central doctrines of economics are not simple and cannot be made so.

In the absence of any short term in common use to represent all desirable things, or things that satisfy human wants, we may use the term Goods for that purpose.

All wealth consists of desirable things; that is, things which satisfy human wants directly or indirectly: but not all desirable things are reckoned as wealth.

Knowledge is our most powerful engine of production.

And very often the influence exerted on a person's character by the amount of his income is hardly less, if it is less, than that exerted by the way in which it is earned.

The most valuable of all capital is that invested in human beings