|The enso in Zen Buddhism suggestd emptiness.|
It is one of the 18 chief kinds of insight or vipassanā meditations (cf. The Path of Purification, Vis.M. XXI).
Suñña (adj.), suññatā (noun), in Sanskrit shunyata, is the verifiable fact that all things are void, empty, devoid of "self."
The phenomena that constitute all things (in particular "self") reveal that they are composite formations, constructions, fabrications:
"Void is the world...because it is devoid of a self and anything belonging to a self" -- suññam attena vā attaniyena vā (S. XXXV, 85).
This is also said of the Five Aggregates clung to as Self (khandha) in the same text. See also MN 43, MN 106.
|The ultimate truth is liberating, but we fear it.|
"Eye, ear, nose, tongue, body, mind, visual objects, auditory objects... mind-objects, visual consciousness, auditory consciousness... mind-consciousness, corporeality... consciousness, and so on -- are devoid of self and anything belonging to a self; void of permanence and anything lasting, eternal, or immutable... They [all phenomena clung to as self] are impersonal: without a core of permanence, a core of satisfaction [the ability to yield fulfillment], or a core of self."
See Sn.v.1119; MN 121; MN 122 (Wheel #87 at BPS.lk); Pts.M. II: Suñña-kathā; Vis.M. XXI, 53ff.
|There are progressive stages of awakening.|
One is an emptying of the mind for its purification, serenity that leads to the progressive meditative absorptions (zens, jhanas, dhyanas, seons, channas, chans).
One attains this purified state of consciousness, emerges, and applies a systematic contemplation of the phenomena called the "Five Aggregates clung to as Self":