Full Idea
Thing in itself signifies that which exists independently of our perception, that which actually is; …to Kant it was '= x'; to me it is will.
Gist of Idea
For me the objective thing-in-itself is the will
Source
Arthur Schopenhauer (Parerga and Paralipomena [1851], IV:61)
Book Reference
Schopenhauer,Arthur: 'Essays and Aphorisms [from Pand P]', ed/tr. Hollingdale,R.J. [Penguin 1970], p.55
A Reaction
Does he mean his own will, which is plausible since he has direct experience of it, or is he referring will in general - whatever that is?