This ancient proverb, 'know the other side and yourself, and you will not be in danger in a hundred battles', teaches us the importance of understanding ourselves and others.

This is a 六角四片四角孔ねじれ正多面體, in other words, a muoctahedron.

He warned the young people, saying 'At thirty, one should not be careless, at forty, one should not be indecisive.'

The 24-cell is one of the geometric shapes in four dimensions.

The 正二十四胞體 is one of the regular polytopes in four dimensions.

Before starting a new business, he said, 'Nothing ventured, nothing gained.'

The Uniform Resource Locator indicates the address of a web page.

He faced difficulties with the spirit of 'one eye, two feet, three gallbladders, four strengths'.