Full Idea
There is a connection among our appearances that provides us the means to predict future appearances with success, and this connection must have a constant cause.
Gist of Idea
The connection in events enables us to successfully predict the future, so there must be a constant cause
Source
Gottfried Leibniz (Letters to Foucher [1675])
Book Reference
Leibniz,Gottfried: 'Philosophical Essays', ed/tr. Arlew,R /Garber,D [Hackett 1989], p.4