Full Idea
Readiness-to-hand is the way in which entities as they are 'in themselves' are defined ontologico-categorially.
Gist of Idea
Readiness-to-hand defines things in themselves ontologically
Source
Martin Heidegger (Being and Time [1927], I.3.15)
Book Reference
Heidegger,Martin: 'Being and Time' [Blackwell 1962], p.101
A Reaction
I assume this is a direct reference to the problem idealists had with the thing-in-itself. It seems that the reality of a thing consists of the strengthened relationship it has with Dasein, which sounds fairly idealist to me.
Related Idea
Idea 22160 Our relationship to a hammer strengthens when we use [Heidegger]