Legend has it that the Eight Trigrams originated from ancient observations of the natural world. The I Ching's "Great Treatise" says, "They took examples near at hand from their own bodies, and from things at a distance." This shows that the ancients derived eight basic symbols from themselves and their surroundings. The method is "taking images to compare categories" — grouping things with similar natures under the same trigram. For instance, strong and dynamic phenomena are typically assigned to Qian, while gentle and receptive ones go to Kun. Each trigram consists of three lines (yáo); different arrangements of solid (yang) and broken (yin) lines create eight archetypal energies. The core of these correspondences is to build an associative framework that "uses symbols to illuminate principles," making abstract natural laws tangible. Importantly, this is a cultural symbolic system reflecting ancient observation and classification, not scientific law — it’s best appreciated as a window into Eastern philosophy.

Qian symbolizes "Heaven," representing strength, initiative, and leadership. In terms of people, it often corresponds to the father or an elder, and temperament wise it leans toward decisiveness and ambition. Dui symbolizes "Lake" or "Marsh," evoking gathering water, and carries qualities of joy, speech, and communication. It's often linked to a young girl, with a bright, lively disposition. Li symbolizes "Fire," with meanings of light, attachment, and civilization. It corresponds to a middle daughter and is associated with beauty, literary grace, and radiance; temperamentally it values external expression and passion. Zhen symbolizes "Thunder," representing vibration, arousal, and action. It corresponds to the eldest son, with an active, impulsive nature. These four trigrams display a spectrum from firmness to movement, each with distinct personality, reflecting the ancients' observation of active forces in the outer world.

Xun symbolizes "Wind," with qualities of penetration, compliance, and entry. It corresponds to the eldest daughter, with a gentle, flexible nature and good coordination skills. Kan symbolizes "Water," representing danger, flow, and wisdom. It corresponds to the middle son, with a deep, contemplative temperament, often linked to adversity and concealment. Gen symbolizes "Mountain," meaning stillness, obstruction, and stability. It corresponds to the youngest son, with a calm, reserved character and a tendency to stop and preserve. Kun symbolizes "Earth," representing gentleness, receptivity, and support. It corresponds to the mother, with a generous, practical nature. These four trigrams lean toward introversion, softness, and stability. Together with the previous four, they form a complete system where strength and gentleness, motion and stillness complement each other — embodying the I Ching's holistic view of yin-yang balance.