Question

why is secular leterature an important source of history

Answer 1

Source literature is a term with different meanings. Literature (understood as printed texts) is one kind of information source. In a way, all literature is a kind of source literature. It might, for example, be cited and used as sources in academic writings. However, if used in this broad meaning the concept becomes synonymous with literature and the term thus superfluous and meaningless.

Answer 2

it is an important source help us to collaborate with other sources and scurtnizing the facts