Sun Jian began his career as a minor local official in his youth, later joined General Zhu Jun of the Eastern Han Dynasty to suppress the Yellow Turban Rebellion, allied with Yuan Shu to attack Dong Zhuo, and gradually amassed a large army through the warlord conflicts.
A woman surnamed Wu lost her parents early in life. When Sun Jian heard she was both talented and beautiful, he sought to marry her, but her relatives deemed him frivolous and cunning and refused. She told them, "Sun Jian holds power—do not offend him on my account. If he treats me poorly after marriage, that is my fate." She wed Sun Jian and bore him four sons and one daughter.
When Sun Jian's wife was pregnant with their first son, Sun Ce, she dreamed of the moon falling into her arms. Later, while carrying Sun Quan, she dreamed of the sun falling into her arms. She asked Sun Jian, "Why did I dream of the moon with my first pregnancy and the sun with my second?" Sun Jian replied joyfully, "The sun and moon are the essence of yin and yang, symbols of great fortune. Our children will surely rise to wealth and honor!"
Indeed, Sun Ce later fulfilled his father's ambition, leading his army across the Yangtze River to crush the warlords in the middle and lower reaches, seizing six commanderies including Wu, Kuaiji, and Lujiang, and establishing the Sun family regime in Jiangdong. In 229 AD, Sun Quan ascended the throne, becoming the first emperor of the Wu Kingdom during the Three Kingdoms period.
Later, the idiom "Sun and Moon Entering the Bosom" came to refer to an auspicious omen of bearing a royal or noble son.
Source: *Records of the Three Kingdoms*, "Biography of Lady Wu, Sun Po's Wife"
Meaning of the Idiom: Later, the Chinese idiom "日月入怀" came to describe an auspicious omen of bearing a royal or noble son.