Emptiness and fullness

Emptiness and fullness (허실, heosil) is a paired concept in the vocabulary of kumdo. It combines sil (實, fullness) and heo (虛, emptiness).

The glossary of the Korea Kumdo Association (대한검도회) defines sil as a state in which the spirit is fully focused and there is no carelessness. Heo is the opposite state, when mind and body are unprepared. Where there is sil there is always heo, and where there is strength there is always weakness. For this reason, aiming at the heo matters in a match. Another formulation in the same vocabulary calls heo the state in which a gap (teum, 틈) has opened in the posture of the mind or the body, and sil the reverse.

• 색 (色, saek): the glossary says it corresponds to heo. It is a sign that appears in a soft, non-rigid way. For example, when the opponent shows no gap, one may display a technique and an opening to lure the opponent in. This is also called saek.
• 틈 (隙, teum): a careless state in which one can be attacked. It often appears when a movement begins, when physical strength and spirit run out, or when a technique fails. It can also relate to breathing, gaze or mental state. Gaps of mind, posture and movement are distinguished. A gap can be created by attacking, or the opponent may show it unprompted.

Japanese sources on the same concept add the following. Feints, meaning movements without real substance, count as heo. Exhaling is associated with sil and inhaling with heo. The instant of launching a technique is a moment of heo, even for a strong opponent. One of them sums up the principle this way: create a state of sil in oneself, avoid the opponent's sil and strike the opponent's heo, while taking care to leave no heo of one's own.