They understand that to consume the goods and services necessary for their own sustenance and enjoyment, they must first produce them by means of their capital and labor.

FORBES: A Revealing Ad Exposes The Department Of Energy's Hypocrisy

In general, the idea is to consume only the amount of phenylalanine that's necessary for normal growth and body processes, but no more.

CNN: Phenylketonuria (PKU)

Here the low price of petrol, much less than half of that in other developed countries, has predictably resulted in ever-larger and heavier vehicles that consume more fuel and road, and generate more pollution, than is necessary.

ECONOMIST: Faulty fuel pump