John Burroughs 
Breath of Life [PDF ebook] 

Much of the time, our bodies carry out the process of respiration without our conscious involvement. But when you stop to really ponder the miraculous nature of breathing, as author John Burroughs does at length in The Breath of Life, this seemingly automatic act takes on greater meaning and significance. This volume is recommended for anatomy buffs, those with an appreciation for natural philosophy, and readers who are interested in exploring the benefits of deep-breathing techniques.