Full Idea
The truth of sensible things is established by the links amongst them; these depend upon intellectual truths, grounded in reason, and upon observations of regularities among sensible things themselves, even when the reasons are not apparent.
Gist of Idea
Truth arises among sensations from grounding reasons and from regularities
Source
Gottfried Leibniz (New Essays on Human Understanding [1704], 4.11)
Book Reference
Leibniz,Gottfried: 'New Essays on Human Understanding', ed/tr. Remnant/Bennett [CUP 1996], p.444
A Reaction
It's not clear why regularities would establish truths, given that most hallucinations have regularities in them. I'm thinking that Leibniz is not sufficiently rationalist here, and that it is the rational coherence of experience which validates it.