This is the famous saying of the ancient Greek philosopher Heraclitus-"The sun is new every day"

(about 540 BC-about 480 BC), the theory that everything is in a rheological state has a great influence on later generations. In his view, the picture presented by the whole world is "everything flows and everything is not born". He used the metaphor of a flowing river to illustrate that nothing in the world is fixed. So he said, "People can't step into the same river twice" and "We can't step into it".

It means:

The sun is new every day and life is always full of hope.