大道之行，天下为公。这句话出自《礼记·大同篇》，是中国古代哲学思想的重要表现之一。所谓大道，是指一种统一的道德规范和价值观念，是人类社会发展的基石。

大道之行，指的是这种道德规范和价值观念的实践和推广。而天下为公，则是表明这种道德规范和价值观念的普适性和公正性，即应该适用于所有人，不论其身份、地位和国籍。

这句话所表达的思想，强调了人类社会应该追求的道德目标，即建立一个公正、平等、和谐的社会秩序。这种道德规范和价值观念，不仅适用于个人的行为，也应该贯穿于整个社会的发展和治理过程中。

在当代社会，大道之行的意义更加深远。随着全球化的加速和国际交往的日益频繁，不同文化、不同民族之间的理解和交流变得更加重要。大道之行不仅是中国的传统文化，也是一个普遍的价值观念，应该成为全人类共同的追求。

译文：

The great way is universal, and the world belongs to everyone. This sentence comes from the 'Book of Rites - The Great Unity' and is an important expression of ancient Chinese philosophical thought. The so-called 'great way' refers to a unified moral norm and value concept, which is the cornerstone of the development of human society.

'The great way' means the practice and promotion of this moral norm and value concept. 'The world belongs to everyone' indicates the universality and fairness of this moral norm and value concept, which should be applicable to everyone, regardless of their status, position, and nationality.

The idea expressed in this sentence emphasizes the moral goals that human society should pursue, that is, to establish a just, equal, and harmonious social order. This moral norm and value concept should not only apply to individual behavior, but also run through the entire process of social development and governance.

In contemporary society, the meaning of 'the great way' is even more profound. With the acceleration of globalization and the increasing frequency of international exchanges, understanding and communication between different cultures and ethnic groups have become more important. 'The great way' is not only a traditional Chinese culture, but also a universal value concept, which should be a common pursuit of all mankind.