for the business of nature is to furnish food to that which is born, and the food of the offspring is always what remains over of that from which it is produced.
 Aristotle, Politics (4th century BC). copy citation

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Author Aristotle
Source Politics
Topic food business
Date 4th century BC
Language English
Reference
Note Translated by Benjamin Jowett
Weblink http://classics.mit.edu/Aristotle/politics.html

Context

“so in one way the art of household management, in another way the subordinate art, has to consider about wealth. But, strictly speaking, as I have already said, the means of life must be provided beforehand by nature; for the business of nature is to furnish food to that which is born, and the food of the offspring is always what remains over of that from which it is produced. Wherefore the art of getting wealth out of fruits and animals is always natural. There are two sorts of wealth-getting, as I have said; one is a part of household management, the other is retail trade:” source