"Few will doubt that humankind has created a planet-sized problem for itself. No one wished it so, but we are the first species to become a geophysical force, altering Earth's climate, a role previously reserved for tectonics, sun flares, and glacial cycles. We are also the greatest destroyer of life since the ten-kilometer-wide meteorite that landed near Yucatan and ended the Age of Reptiles sixty-five million years ago. Through overpopulation we have put ourselves in danger of running out of food and water. So a very Faustian choice is upon us: whether to accept our corrosive and risky behavior as the unavoidable price of population and economic growth, or to take stock of ourselves and search for a new environmental ethic."

“The naturalist is a civilized hunter. He goes alone into the field or woodland and closes his mind to everything but that time and place, so that life around him presses in on all the senses and small details grow in significance. He begins the scanning search for which cognition was engineered. His mind becomes unfocused, it focuses on everything, no longer directed toward any ordinary task or social pleasantry.”

“Will we solve the crises of next hundred years? asked Krulwich. “Yes, if we are honest and smart,” said Wilson. “The real problem of humanity is the following: we have paleolithic emotions; medieval institutions; and god-like technology. And it is terrifically dangerous, and it is now approaching a point of crisis overall.” Until we understand ourselves, concluded the Pulitzer-prize winning author of On Human Nature, “until we answer those huge questions of philosophy that the philosophers abandoned a couple of generations ago—Where do we come from? Who are we? Where are we going?—rationally,” we’re on very thin ground.”

“The worst thing that can happen during the 1980s is not energy depletion, economic collapse, limited nuclear war, or conquest by a totalitarian government. As terrible as these catastrophes would be for us, they can be repaired within a few generations. The one process ongoing in the 1980s that will take millions of years to correct is the loss of genetic and species diversity by the destruction of natural habitats. This is the folly that our descendents are least likely to forgive us.”

“The most peaceable tribes of today were often ravagers of yesteryear and will probably again produce soldiers and murderers in the future.”

“Animals use aggression as a technique for gaining control over necessities... that are scarce or are likely to become so... They intensify their threats and attack with increasing frequency as the population around them grow. As a result the behavior itself induces members of the population to spread out in space, raises the death rate, and lowers the birth rate. In such cases aggression is said to be a "density-dependent factor" in controlling population growth.”

“A schema is a configuration within the brain, either inborn or learned, against which the input of the nerve cells is compared. ...the conscious mind ...can fill in details that are missing from the actual sensory input and create a pattern in the mind which is not necessarily present in reality. In this way, the gestalt of objects—the impression...—is aided by the taxonomic powers of the schemata.”