Full Idea
If that substantial chain [vinculum substantiale] for monads did not exist, all bodies, together with all of their qualities, would be nothing but well-founded phenomena, like a rainbow or an image in a mirror, continual dreams perfectly in agreement.
Gist of Idea
Without a substantial chain to link monads, they would just be coordinated dreams
Source
Gottfried Leibniz (Letters to Des Bosses [1715], 1712.02.05)
Book Reference
Leibniz,Gottfried: 'Philosophical Essays', ed/tr. Arlew,R /Garber,D [Hackett 1989], p.198
A Reaction
[The first appearance, apparently, of the 'susbtantial chain' in his writings] I take this to be a hugely significant move, either a defeat for monads, or the arrival of common sense. Spiritual monads must unify things, so they can't just be 'parallel'.
Related Ideas
Idea 12753 A substantial bond of powers is needed to unite composites, in addition to monads [Leibniz]
Idea 12777 Monads do not make a unity unless a substantial chain is added to them [Leibniz]
Idea 12778 There is active and passive power in the substantial chain and in the essence of a composite [Leibniz]