What is the relationship between natural light and the lives of humans and animals?

In “the things they carried”, why is jimmy unsure when martha calls the pebble “a token of her truest feelings”

Something you may do if the weather's nice on sunday. -something you might not want to do this evening. -something you could go on aaturday evening. -something you could wear to a party. -somebody you might see in the next couple of days. -a subject you could study at college or university. -somewhere you might go on holiday .

How does the literature of this period influence future generations of american literature? where have you seen traces of these themes and how were they presented in the other literature you read?