Full Idea
In a true proposition the concept of the predicate is always present in the subject.
Gist of Idea
The predicate is in the subject of a true proposition
Source
Gottfried Leibniz (Letters to Antoine Arnauld [1686], 1686.07.4/14 X)
Book Reference
Leibniz,Gottfried: 'The Leibniz-Arnauld Correspondence', ed/tr. Mason,HT/Parkinson,GHR [Manchester UP 1967], p.58
A Reaction
This sounds very like the Kantian notion of an analytic truth, but Leibniz is applying it to all truths. So Socrates must contain the predicate of running as part of his nature (or essence?), if 'Socrates runs' is to be true.
Related Idea
Idea 19333 A truth is just a proposition in which the predicate is contained within the subject [Leibniz]