Liberation is signless not a sensation, emotion or thought. The gates are signless, desirelessness and emptiness. "uncertainty" is the approach to these gates.
Our mind /body is held in the grip of kamma, framed by anxiety, grief and other forms of dukkha. Mindfulness replaces this frame with clear, emphatic awareness.
This is the second discourse given by the Buddha to his five original ascetic companions after setting the wheel of the Dharma in motion. The Buddha gives his teaching on Anatta (or not-self), and the five become enlightened.
