In the West, Stoics like Marcus Aurelius taught that the universe and the soul are reflections of the same order, that wisdom lies in understanding one's role within the whole. In China, centuries earlier, Zhang Zai stood beneath the sky and arrived at a similar revelation—one that would echo through all later philosophy.
Northern Song Dynasty, around 1070 CE
The plains of Hengqu stretched wide under the autumn sun. Zhang Zai, known for his quiet gaze and unshakable calm, stood before his students as wind stirred the reeds beside the river. He looked not at the scrolls they held, but at the horizon itself.
"Do you see the sky?" he asked. "It shelters all without preference. And the earth—does it choose whom it bears? Then how should man, between heaven and earth, live?"
The students exchanged puzzled looks. Zhang Zai smiled, took up his brush, and wrote four simple lines upon a stone tablet:
Heaven is my father, Earth is my mother;all beings are my brothers and sisters.The wise must continue the lost teachings of the ancients,and bring peace to all future generations.
He laid the brush down. "This," he said softly, "is not a doctrine—it is a way of seeing."
In that moment, the wind shifted, carrying the scent of soil and rain. One student bowed deeply. "Master, does this mean we must serve all life?"
Zhang Zai's eyes gleamed. "To serve life," he said, "is to understand it. When the heart embraces all under Heaven, even sorrow becomes harmony."
That night, he sat alone by lamplight, staring at the stars beyond his window. The world, vast and unending, felt close—as though the cosmos itself whispered through his ink. His words would later be called the Four Sentences of Hengqu, but to him, they were simply the echo of unity between man, heaven, and earth.
As dawn broke over Hengqu, Zhang Zai's words scattered like light upon the river—clear, steady, enduring. Generations later, one scholar would gather those fragments of wisdom and shape them into a grand system of thought. His name was Zhu Xi, and in his classrooms, the moral pulse of Chinese philosophy would once again come alive.