Full Idea
Of things that come under one Idea there is one single science, so there should be some one science of all good things; but in fact there are more than one science even of those that fall under one category (e.g. opportunity in medicine and in war).
Gist of Idea
There should be one science of the one Good, but there are many overlapping sciences
Source
Aristotle (Nicomachean Ethics [c.334 BCE], 1096a27)
Book Reference
Aristotle: 'Ethics (Nicomachean)', ed/tr. ThomsonJ A K/TredennickH [Penguin 1976], p.70
A Reaction
The reply might be that there are many sciences because humans are confused. A truly wise person would see that the science of opportunity is the same in medicine and war. If the good was pleasure, or the glory of God, this would be obvious.