What is the theme in The World Turned Upside Down: Indian Voices from Early America by Colin G. Calloway?

Part of the disconnect between European and Indian cultures was European reliance on the written word and the Indian reliance on the spoken word. Europeans had long relied on written contracts in their legal system and elsewhere to formalize agreements, and this came into play with the great many land deals made during the 17th and 18th centuries. Europeans came from a system and culture that ignored or greatly downplayed any verbal negotiations made prior to a final written contract.