Full Idea
Betwixt unity and number there can be no medium; no more than betwixt existence and non-existence.
Gist of Idea
There is no medium state between existence and non-existence
Source
David Hume (Treatise of Human Nature [1739], I.IV.2)
Book Reference
Hume,David: 'A Treatise of Human Nature', ed/tr. Selby-Bigge/Nidditch [OUP 1978], p.200
A Reaction
Just to confirm that, as you would expect, the great empiricist has no time for 'subsistence', or shadows and holes having lower grade existece.