In Chinese philosophy Yin & Yang are two comlementary yet opposite forces which are manifest in all things. Yin may be understood as anything negative, passive, feminine, soft etc and Yang may be understood as anything positive, active, masculine, hard etc. The symbol for Yin & Yang is known as T'ai Chi (supreme ultimate) and represents the constant flow from one to the other.
The main difference between Western and Eastern philosophy is that in the West people view things as seperate and opposite. For instance light and dark are opposite. However in the East things are viewed differently. Everything is ultimately viewed as being a part of one whole which is referred to as Tao, which can be translated roughly as meaning Way, Essence, Path, Force etc. So the Chinese understand Yin and Yang being two complementary aspects of one whole. You cant have one without the other. For instance now it may be dark, but to understand darkness I must know what light is. So they are two different ways of describing the sky, which is one thing.
The main difference between Western and Eastern philosophy is that in the West people view things as seperate and opposite. For instance light and dark are opposite. However in the East things are viewed differently. Everything is ultimately viewed as being a part of one whole which is referred to as Tao, which can be translated roughly as meaning Way, Essence, Path, Force etc. So the Chinese understand Yin and Yang being two complementary aspects of one whole. You cant have one without the other. For instance now it may be dark, but to understand darkness I must know what light is. So they are two different ways of describing the sky, which is one thing.
So basically something cannot be pure Yin or Yang, it always contains elements of both. Also it must be understood that Yin & Yang are not static, like everything in existence they are impermanant and cannot be understood intellectually, only felt. For instance if I ride my bike I cannot pedal on both pedals at once, I must push one and release one, so I am using both Yin & Yang together to move.
So, how is this relevant to Wing Chun. Well, we all know that you cannot overcome strength with strength. So in Wing Chun we must be soft and compliment the opponents movement, so he leads to his own destruction. A perfect example of this would be a Lap Sau & punch. As the opponent punches towards me I grab his arm and pull it towards me, while turning and punching, so I am not opposing his force, only gently guiding it past me, then returnin it to him with my fist. This way I am using his own force against him. Also Yin & Yang are evident in every movement we make. We have 2 types of energy in Wing Chun, Gung Lik (hard, forward energy) & Sun Lik (soft, withdrawing energy). These are opposites, but complementary. We should never purely use one or the other, only combine them together. For instance, Bong Sau is a soft technique, but it moves forward before collapsing, so it contains elements of both. As you progress through your training you will discover how Yin & Yang interplay in every movement made, at first through Chi Sau, then through forms.
