Science has given us tools and methods that allow us to observe things that were once imperceptible--and this book shows what we can learn when we use them to look at ourselves. Written by science journalist Gary Wolf, co-founder of the Quantified Self movement, this book teaches readers how to use proven scientific methods to answer their own health questions. At a time when trust in expertise is fractured and people are divided not just politically but over how to know what's true, The Quantified Self makes the case that science belongs to everyone--and proves it by putting the method in the reader's hands. Wolf teaches ten reasoning patterns adapted from the history of scientific practice and illustrates them with dozens of personal narratives. Across chapters on pain, mood, cognition, sleep, digestion, heart health, and hormones, readers learn a practical method for answering the health questions that matter most to them.