Edward O. Wilson is a great biologist, a great conservationist and a great optimist. He thinks we should set aside half the planet as wilderness, and he believes we can do it. In this new book, he tells the story of a nature preserve in Mozambique to make his case.

“A Window on Eternity” is a short coffee-table book, with lots of wildlife photographs and lots of white space on the page. But it is more than a casual addition to his shelf of almost 30 books, two of which have won Pulitzer Prizes. Dr. Wilson’s visits to Gorongosa National Park and its summit, Mount Gorongosa, have been capstone experiences for him. It is not too much to say that he fell in love with the mountain at the age of 81.

Gorongosa was probably one of the first peaks our species ever saw. It stands at the southern end of the Great Rift Valley in the middle of a rain forest. Stone Age tools have been found on its slopes. For much of the 20th century it was a popular tourist destination, attracting big-game hunters and big-time movie stars. Then came disaster.

Gorongosa means “place of danger,” and from 1976 to 1992 its wildlife was decimated by Mozambique’s civil war. Soldiers slaughtered the elephants for ivory, and the lions for sport. They butchered the Cape buffaloes, hippopotamuses, warthogs and antelopes. By the time the fighting ended, most of the big animals left were crocodiles.