Full Idea
The order and connection of ideas is the same as the order and connection of things.
Gist of Idea
Ideas and things have identical connections and order
Source
Baruch de Spinoza (The Ethics [1675], II Pr 07)
Book Reference
Spinoza,Benedict de: 'Ethics', ed/tr. White,WH/Stirling,AH [Wordsworth 2001], p.50
A Reaction
I hadn't registered until Beth Lord pointed it out that this is Spinoza's parallelism of the mental and the physicalism, which seems to be roughly the same as the views of Leibniz and Malebranche, but with a different explanation.