From the Ocean of Dharma Blog:
Buddha nature is not regarded as a peaceful state of mind or, for that matter, as a disturbed one either. It is a state of intelligence that questions our life and the meaning of life. It is the foundation of a search. A lot of things haven’t been answered in our life—and we are still searching for the questions. The questioning is buddha nature. It is a state of potential. The more dissatisfaction, the more questions and more doubts there are, the healthier it is, for we are no longer sucked into ego-oriented situations, but we are constantly woken up.