Thanks to the readers of my previous book, Inner Algebra, for valuable feedback. Thanks to my friend Sarah Hwang for helping with the title and cover. (The results are much better than my original ideas!)
I'd like to express my gratitude to the worldwide community of free and open source software developers. This book was written and typeset using open source software, including the LYX editor (along with the memoir document class), the LATEX typesetting system, the GIMP image editor, and the Debian GNU/Linux operating system (with all of its supporting software). This is the fruit of the cumulative, generous efforts of a large number of software developers, who over many years donated their time to help create the software used every day by myself and many others. Thank you.