This is a exploration of human cultural/ethical systems by Jane Jacobs, a specialist in municipal politics and sociology. It is based on the assumption that human society is necessarily a function of the symbiosis between the protective or preservative (Guardian) function and the creative (Trader) function. Like many "theories of humankind", it should be taken with a grain of salt but reading the book can provide insights, and perhaps can be useful for devising characters and their role.. The values proper to each role are according to the author: Trader: Guardian: Some Guardian Characters: