Full Idea
By these marks we distinguish what comes naturally: everything that is there straightaway as soon as something comes to be, and all that occurs to us if growth is allowed to proceed normally - such as greying hair, ageing, and the like.
Gist of Idea
What is natural for us is either there at birth, or appears by normal processes
Source
Aristotle (Eudemian Ethics [c.333 BCE], 1224b32)
Book Reference
Aristotle: 'Eudemian Ethics I,II and VIII', ed/tr. Woods,Michael [OUP 1992], p.26
A Reaction
The word 'normal' has to do a lot of work here. Presumably jaundice in a neonate is not included. Or later hereditary diseases.
Related Idea
Idea 22510 Some emotional states are too strong for human nature [Aristotle]