What is the life thinking in Nineteen Ancient Poems?

Nineteen Ancient Poems thoroughly reveals many philosophies of life, and the author's understanding of the true meaning of life makes these poems profound, poetic and speculative. Specifically, there are mainly the following life thoughts: 1. The relationship between eternity and finiteness. The feeling of limited life has existed since ancient times. 2. The relationship between people's mentality and life cycle. For example, "thinking of a gentleman makes people old." 3. The relationship between melancholy and joy. For example, "if you are born less than 1 years old, you will always be worried about being a thousand years old." "If you are happy in time, how can you stay here?" 4. the relationship between coming and going. For example, "if you go, you will be sparse, and if you come, you will be close."