Full Idea
No more need be demanded of 'is square' than that our listener learn when to expect us to apply it to an object and when not; there is no need for the phrase itself to be the name in turn of a separate object of any kind.
Gist of Idea
Understanding 'is square' is knowing when to apply it, not knowing some object
Source
Willard Quine (Identity, Ostension, and Hypostasis [1950], 4)
Book Reference
Quine,Willard: 'From a Logical Point of View' [Harper and Row 1963], p.75