What is the meaning of the word "constant" in "five constants"? Specific!

Confucius and Mencius put forward "benevolence, righteousness, propriety, and wisdom", and Dong Zhongshu expanded it to "benevolence, righteousness, propriety, wisdom, and trust", which is called the "Five Constants".

"Constant" is also constant, and its spirit can transcend the region and the times and last forever. This is the understanding of the ancients. However, it is also true that the "five constants", as an important part of the main body of Chinese ethics, have been present throughout the development of Chinese ethics. They are not only a kind of moral norms, but also form a kind of moral consciousness and concepts, as the most central element of the traditional Chinese value system, which has influenced people for more than 2,000 years in the Chinese land, and has become the constituent elements of the national spirit, and has become the root of the spirit and culture of Chinese people all over the world, and is an important factor for the Chinese culture to play the role of cohesive agent.