Like nearly every area of scholarly inquiry today, the biological sciences are broken into increasingly narrow fields and subfields, its practitioners divided into ecologists, evolutionary biologists, taxonomists, paleontologists, and much more. But all these splintered pieces have their origins in the larger field of natural history-and in this era where climate change and relentless population growth are irrevocably altering the world around us, perhaps it's time to step back and take a new, fresh look at the larger picture.

"The Essential Naturalist" offers exactly that: a...