Full Idea
Frege equated the concepts under which an object falls with its properties.
Gist of Idea
Frege equated the concepts under which an object falls with its properties
Source
report of Gottlob Frege (On Concept and Object [1892], p.201) by Michael Dummett - Frege philosophy of mathematics Ch.8
Book Reference
Dummett,Michael: 'Frege: philosophy of mathematics' [Duckworth 1991], p.98
A Reaction
I take this to be false, as objects can fall under far more concepts than they have properties. I don't even think 'being a pencil' is a property of pencils, never mind 'being my favourite pencil', or 'not being Alexander the Great'.