The human cannot return to nature, There is too much beyond us which we cannot return. Signs, tools, and above all, promise. To promise is to prescribe a duty, and offer one's reputation as collateral. It implies trust, it assures that one will act in accordance with their word.
What should make this anything other than an elaborate set of signs used to measure the value of other humans? An intricate social tool, as it were.
In promise there is a prescription of duty towards another, and an invocation of hope. In promise there is subordination, implied trust.
They say agreements must be kept, unless they are worth less to others than a new option is to you.