The journey of a thousand miles begins with one step.

A wise man said: before you speak， let your words pass through three gates. At the first gate， ask yourself， "Is it true？" At the second gate， ask "Is it necessary？" At the third gate， ask， "Is it kind？"

Old soldiers never die. They just fade away.

解释：处于安全环境时要考虑到可能出现的危险，考虑到危险就会有所准备，事先有了准备就可以避免祸患。