To start at the beginning, we must know where we are going. This Prologue establishes an informal taxonomy of digital or virtual human types. They are not all imagined equal, and three particular dimensions are singled out to order the complexity in modeling humans. We establish that this origin story is going to be oriented to the personal experiences of the author, and not attempt to be a survey of the modern landscape of virtual human activities, software, and applications. Nonetheless, the different dimensions of the taxonomy lead to different characteristics and perhaps a better understanding of what is relatively easy and what is hard, where we have been and where we are going.