Emptiness is the key, because emptiness is the sphere which is denied. Form is easily recognised and there is experience with manipulating form, but there is a disconnection and lack of experience of the sphere of emptiness. This disconnection can be overcome through meditation practices that introduce the experience of emptiness, either through analysis or examination. Emptiness can also be discovered through both happy and sad life experiences. The sphere of emptiness can become available through devoted relationship with a teacher.
Battlecry of Freedom by Ngakma Nor’dzin, Aro Books worldwide, 2019, ISBN 978-1-898185-46-8 Part II - the slogans, p. 93