Full Idea
He who can finally make predictions with success must be said to have become sufficiently proficient in nature.
Gist of Idea
Successful prediction shows proficiency in nature
Source
Gottfried Leibniz (On Perceptions [1680], A6.4.1398), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 7
Book Reference
Garber,Daniel: 'Leibniz: Body, Substance, Monad' [OUP 2009], p.280
A Reaction
Is prediction achieved by knowledge of laws, or knowledge of essences and powers? The trouble with most laws is that they permit exceptions. 'Things fall, unless prevented' etc.