If you’ve made it this far into the book—to the last chapter in part 3—it is likely you have concluded that the self-sovereign identity (SSI) technology and philosophy play at the edges of possibility about how the world can be organized. Bitcoin and the blockchain movement have opened up the discussion about what money is beyond its traditional boundaries; SSI is doing the same for identity. Our aim in part 3 has been to introduce these movements’ inner workings and how they inspire each other. One of the identity pioneers who has pushed the boundaries of what is possible even further is David Birch, a world-renowned expert in both digital identity and payments and author of the book Identity Is the New Money (http://www .dgwbirch.com/words/books/identity-is-the-new-money.html; see also his more recent book, Before Babylon, Beyond Bitcoin: https://beforebabylonbeyondbitcoin .com). David inspired us to share with you how the combination of these two fundamental tools of social organization can be combined in this accelerating process of technological change to disrupt the way we think about these concepts.