Full Idea
To first order modal logic (with quantification over objects) we can add a second kind of quantification, over intensions. An intensional object, or individual concept, will be modelled by a function from states to objects.
Gist of Idea
Intensional logic adds a second type of quantification, over intensional objects, or individual concepts
Source
Melvin Fitting (Intensional Logic [2007], 3.3)
Book Reference
'Stanford Online Encyclopaedia of Philosophy', ed/tr. Stanford University [plato.stanford.edu], p.14