Full Idea
Only the will is thing-in-itself. ...It appears in every blindly acting force of nature, and also in the deliberate conduct of man, and the great difference between the two concerns only the degree of the manifestation.
Gist of Idea
Only the will is thing-in-itself, seen both in blind nature and in human action
Source
Arthur Schopenhauer (The World as Will and Idea [1819], I 110), quoted by Christopher Janaway - Schopenhauer 3 'Will'
Book Reference
Janaway,Christopher: 'Schopenhauer' [OUP 2002], p.37
A Reaction
If will acts 'blindly' in forces of nature, then these seems to be the same concept as Nietzsche's 'will to power'. This seems to be heading towards Heidegger's Dasein, as a central and distinctive mode of being.