The Emptiness of Emptiness

...the Buddha had taught people to free themselves from suffering by realizing the impermanence and interdependence of everything upon which their suffering depended, including and especially themselves. The Buddha called this the realization of shunyata (emptiness), the view that because nothing exists independently of other things, it has no nature of its own, and everything is therefore empty, and this emptiness is the true nature of reality. Later, when the Buddha began teaching people to view emptiness itself as empty and to put the emptiness of emptiness to work for the liberation of all beings, few disciples grasped this new teaching, which he called the perfection of wisdom, the wisdom beyond wisdom.

---Red Pine  in his commentary on the Diamond Sutra---