Ngoc Lu Bronze Drum is about the law of changes whose foundation is the theory of Am Duong Ngu Hanh or Yin Yang Five Elements. Therefore, Am Duong – Yin Yang is depicted widespread on the Drum.
Am Duong on the Drum
In the very center of the drum is a sun with 14 beams. “In the center” implies the inside & hidden. So, Drum shows us that Sun, inside & center are representations of Am.
Moreover, as Am is invisible, it is seamless. As it is seamless, it is big & ubiquitous. Drum describes these Am’s properties with the image of the 16 concentric circles covering whole Drum, representing the Tai Chi or everything.
On the ring No. 10, Drum shows 18 big birds and 18 small birds. The big bird represents Am & the small bird, Duong.
Big bird over small bird expresses the idea that Am is bigger than Dương, and it holds, embraces & covers Duong.
The big bird is flying. Within itself, there is a transformation from trigram Càn in head part to double trigrams of Càn in the tail part. This means Am is alive & transformative internally. However, Am does not change externally, or its form keeps un-changed, indicated by the image of similar 18 large birds.
Standing small bird implies the dullness & lifelessness. In addition, different shapes of 18 birds imply that Duong (Yang) changes form over times.
Regarding the source, on ring No. 1, the Drum indicates that everything starting from Am at the very center, where 14 rays shine out.
Those beams are Am in motion. When Am moves, it is called Khí Dương, positive prana or yang qi. It is not something different but just the movement of Am. That is why the rays cast seamlessly and in the same color as the circle.
When the Am rays move out centrifugally, they gradually become more tangible & manifest in various forms which are classified as Dương i.e. Am has transformed into Duong. Sooner or later, Duong must return, and it does. Drum depicts the returning of Duong with 14 shapes pointing inwardly towards the center. The shape implicitly contains the Late Heaven 8 Trigrams (or everything), as mentioned in the Drum’s Diagrams post. This time, Duong will gradually transform to Am. Duong in the centripetal motion is called Khí Âm or negative prana or yin qi.
Other symbols of Am Duong.
When we say “Trời Tròn Đất Vuông” – Sun (Càn, Heaven) is round and Earth (Khôn) square, it cannot be understood literally that the sun is round, and the earth is square. That sentence carries the philosophical meaning. Sun & Round refer to the absolute, great, infinite, strong, invisible, colorless, voiceless, immortal. Sun, round, circle, heaven, spirit & Càn are the symbol of Am.
In contrast, Earth, Square, Khôn refer to the opposite: tangible, limited, material, lust etc.
Similarly, the two cakes bánh chưng bánh giầy that are very familiar and indispensable to Vietnamese people during Tet holidays carries profound meanings of Vietnamese’s worldview expressed through the tale of the same name. The tale talks about how the 6th Hung King passed the throne to his son, Lang Lieu, who was told by the gods to choose the best sticky rice in the house to make these two cakes as a gift to the King because Lang Lieu is the one who has mastered the Round-Square Tao or the Tao of Am Duong, Yin Yang, Can Khon.
Everywhere, since ancient times people have studied the Universe and its laws. “Am Duong Ngu Hanh” theory or Drum is unique in because they come up with a complete system very early on and use a unique symbols & diagrams to express its Philosophy.
In Shaivism, Shiva is supreme Lord that represents consciousness or spirit. He is infinite, eternal, transcendent, formless, invisible but he can manifest in many forms. Thus, Lord Shiva is equivalent to Âm or Yin. Meanwhile Shakti, the female companion of Lord Shiva, is prana or qi, and equivalent to the Dương or Yang.
With regards to the symbol, different religions & philosophies in the world have always used the Circle as a Symbol of the whole, total, holy, infinite or God1 Source: Symbolism: 9 Common Circle Symbols – Symbolism And Meaning.
Summary
Càn or Sun or Heaven is Am (Yin) and Khôn (Earth), Duong (Yang).
Am & Duong are symbolizing all opposites, conflicting but also complementary & inseparable.
Am is spiritual & formless, hidden & intangible to the senses. It is independent, omnipresent, large and strong because of its seamlessness & wholeness. As a spirit & consciousness, it has the capacity for self-awareness, coupled with its independence it becomes eternal, beginningless, endless, unborn, un-died. Its statue is circular & color is black.
In contrast, Duong refers to physical & forms, tangible & visible to the senses. As such it is dependent, small, weak, occupies a certain position in space-time, has a beginning & an end, birth & death. Its statue is square, color is red or white.
In terms of interactions, both Am & Duong fluctuate & change. Am is alive & transformative internally but unchanged. In contrast, Dương, being dull & rigid but its form changes over times. What is alive in Duong is Am, and what dies in Am is Duong. Am tends to go outward, rise up, move centrifugal. When in motion, its movement is called Khí Dương, Yang Qi or Positive Prana. On the other hand, Duong tends to return, move centripetal, seep down. When moves, its movement is called Khí Âm, Yin Qi or Negative Prana.