This new volume comprises all of Glacken's unpublished writings to follow and covers a broad temporal and geographic canvas, spanning the globe from the mid-eighteenth to the mid-twentieth centuries. Each essay offers a brief intellectual biography of an important environmental thinker and addresses questions such as how many people the Earth can hold, what resources can sustain such populations, and where land for growth is located. This collection—carefully edited and annotated, and organized chronologically—will prove both a classic text and a springboard for further discussions on the history of environmental thought.