What is the theme in Flash Fiction: Very Short Stories by James Thomas?

A number of stories in "Flash Fiction" have themes that focus on youth or the recapturing of one's youth. In "Stones," the writer likes to watch the stones on the desert. The young stones like to move about which worries their elders, especially as the youngsters edge their way to the water. The old stones like to stay put in the warm desert floor and consider all movement as dangerous.