Full Idea
Outside the intellect, there is nothing but substances and their affections.
Gist of Idea
Outside the mind, there are just things and their properties
Source
Baruch de Spinoza (The Ethics [1675], I Pr 04)
Book Reference
Spinoza,Benedict de: 'Ethics', ed/tr. White,WH/Stirling,AH [Wordsworth 2001], p.5
A Reaction
This is pretty close to the very sparse ontology espoused by modern philosophers who take their lead from the logic.