As you know what your motion should be like and you know what points you should attack and what points you should not, then, riding the flow of <Heo> and <Sil>, you can succeed in your attack at the opponent.

What are <Heo> and <Sil>? What has its appearance that has nothing intended in real is called <Heo>, while, on the contrary, what is filled with intention to do something regardless its appearance is called <Sil>. As you know, the "I" is empty, so there can be no constant substantial subject of pursuit so that the counter change of <Heo> and <Sil> in every case continues with no stop relying on its emergent conditions and what each of your and the opponent's will intends. This change is boundless so that it can be compared to that of Yin/Yang of <Yeok> on one hand, while there is no perfect completion at all, on the other hand. Distinguishing something and intending to do it belong only to matters of man who has his own will, so <Heo> and <Sil> are to be discerned with division to a rise or a fall of each. The world, however, cares nothing without what it distinguishes for itself so that <Heo> and <Sil> are mixed in infinite change, thus there is neither what is not <Heo> nor what is not <Sil>. Therefore, the existence of each is also boundless. It is because Taekwondo man wants to imitate this virtue of the world that he erases himself up to delete every distinction on what he desires to do.

Why is it difficult to get control over the opponent with your successful attack at him without riding the change and the flow of <Heo> and <Sil>? It is due to that the opponent whom you face in Taekwondo is not a mere thing like a stone or a wood but a living and moving man, who has what he intends with what he avoids. To live is to adapt yourself. The infinite capacity of adaptation is the substance of life. Since the opponent adapts himself to the change pursuing what he wants you can get easy control over him only when you restrict his adaptation along the flow of <Heo> and <Sil>, through which you can catch him with more ease. This is the difference between catching a fish swimming in water and catching a stone put under water.

How to ride the flow of <HeoSil>? Only after you know how it can be, then you can know how to ride it. Emptyness of what you intend to do is <Heo> while its fullness <Sil>. On the other hand, what is to be filled is <Heo> while what is to be emptied <Sil>. Therefore, <Sil> is followed by <Heo> while <Heol> is by <Sil>. And <Heo> contains <Sil> while <Sil> contains <Heo>. Each of them all cannot be distinguished ultimately. So, you can have <Heo> as <Sil> and <Sil> as <Heo>, and it is most changeful that each of both follows including the other, which makes the flow of <HeoSil>.

As you know all of them you can ride its flow in three ways. To have your tide and balance empty saving your distance with a faint motion of no fullness on one hand, and have yourself prepared for the next motion in your own rhythm i.e. form filled motions hidden by faint motions on the other hand, which is the first. The second is that you should tempt the opponent into your full blind point doing both of erasing and picturing yourself to have him opposed to the world, which is to put a full bait in an empty trap. The third is that you have your empty self opposed to him managing yourself with your full self at the same time, to have <Heo> as <Sil> and <Sil> as <Heo> so that you catch the difference between his <Heo> and <Sil> with the help of the sameness of your <Heo> and <Sil>.

These three ways to control the opponent riding the flow of <HeoSil> are both same and different, and you can know that they are same as you understand TAEKWONDO. If you master how to control <HeoSil> in this manner you will be familiar with the Taekwondo distance. For <Sil> is owing to what you want to do, which, when emptied, makes <Heo>, so that you can have the distance close to the opponent with <Sil> and far from him with <Heo> at once. Therefore, the distance between two Taekwondo men always changes continuously even when they stay standing on their spots like posts.

Your ideal Taekwondo's motion, which rides the flow of <HeoSil>, always avoids the opponent's <Sil> stabbing his <Heo>, and turns your <Heo> to <Sil> along the continuous change. You can find <Heo> of what he thinks with balances of simplicity and complexity. You should find out <Heo> of his motion with harmony of the slow and fast. All of these , when coupled with one another, make the 'preceding attack' with the 'counter attack', and generate the 'faint motion' with the 'filled motion'.

It is called "preceding attack" to precede the opponent's filled preparation so as to stab its <Heo> in a fast tide. The preceding attack should precede three; it should precede his motion, it should precede his waiting and it should precede his expectation. It is called "counter attack" to have yourself harmonized in his attack of big change in <HeoSil> so as to stab his empty point with what you are full of. The counter attack also should catch three; it should catch the crevice of his motion, it should catch what he failed thinking of in his preparation and it should catch what is not firm in his tide.

There is a motion, of which the figure is full, yet of which the substance is empty, and thus which is not an attack even if it looks like an attack and which is not a defense even if it looks like a defense. We call it "a faint motion". To the contrary, there is also a motion, which is a sharp attack at his core as an attack, and which also can be a defense good enough for protection of yourself as a defense, regardless its appearance. We call it "a filled motion". Every motion, even if it might be a faint motion, can turn to a filled motion with no confusion whenever needed, while, on the contrary, every filled motion also can be emptied whenever needed, when there is no distinguishing a faint motion from a filled motion. This is doing both of <Heo> and <Sil> in a motion.

When you stab a <Heo> in his motion you can precede the motion while when you precede his expectation you can stab the <Heo> of his thinking. As there is no difference between preceding his preparation and stabbing his empty part with your fullness there is no difference between a preceding attack and a counter attack either in that manner above.o

The principle that controls every change of <HeoSil> can be summed up in a clause; to stab your <Heo> for yourself in order rather to get control over the opponent. The best way to deceive him is to deceive yourself and if you want to change the world you should change yourself at first. In this way, you can get control over him with no mistake since you are rather empty scattered in truth as you know your own <Heo> allowing it, which is again a perfect <Sil>. Even if each of and looks different to those who make blind distinctions, each is not separated ultimately from the other, and its fundamental essence is the <Heo> in no willing of the world. But in the willing of man the fundamental essence is <Sil>. Therefore, you can get useful <Heo> only after you have gotten <Sil> through continuous training. These are on same principle as of that you can go over distinctions only after you have understood the distinction.