Full Idea
Schopenhauer is not a realist about material things, but an idealist: that is, material things would not exist, for him, without the mind.
Gist of Idea
For Schopenhauer, material things would not exist without the mind
Source
report of Arthur Schopenhauer (Fourfold Root of Princ of Sufficient Reason [1813]) by Christopher Janaway - Schopenhauer 2 'Fourfold'
Book Reference
Janaway,Christopher: 'Schopenhauer' [OUP 2002], p.21
A Reaction
Janaway places his views as close to Kant's, but it is not clear that Kant would agree that no mind means no world. Did Schopenhauer believe in the noumenon?