What do stamps, boat tickets, graves and straits mean in the poem Homesickness?

Stamps-running away from home when I was a child;

Boat ticket-parting with your lover;

Relatives who left the grave;

Strait-lamenting the division of the country.

The author uses the overlap of "small, narrow, short and shallow" to describe the "small" of these four things. Although small, it is difficult to surpass the past, which shows the author's nostalgia for his hometown, his lover and his family, as well as his attachment to the mainland and the motherland since childhood.

Yu Guangzhong,1928101October 2 1 was born in Nanjing, Jiangsu Province, and1moved to Taiwan Province Province in 1949. This poem was written in the early 1970s.