Full Idea
Chance is inexplicable, because explanations can only be given for things that happen either always or usually, but the province of chance is things which do not happen always or usually.
Gist of Idea
Chance is inexplicable, because we can only explain what happens always or usually
Source
Aristotle (Physics [c.337 BCE], 197a19)
Book Reference
Aristotle: 'Physics', ed/tr. Waterfield,Robin [OUP 1996], p.45
A Reaction
This seems wrong. We can explain perfectly well a chance meeting in the market place - it is just that the explanation is not of much use in making future predictions. But we may avoid the market place because of the danger of chance meetings.