"But some numbers, called dimensionless numbers, have the same numerical value no matter what units of measurement are chosen. Probably the most famous of these is the 'fine-structure constant,' .... Physicists love this number not just because it is dimensionless, but also because it is a combination of three fundamental constants of nature."

"The signs of climate change are visible across the nation, from the drought-stricken fields of Central California to the flooded streets of Michigan. Extreme weather is turning people's lives upside down and costing communities millions of dollars in damaged infrastructure and added health care costs."

"As the people of Shishmaref lose their natural hunting grounds to the warming sea, they are forced to buy U.S. Canned goods from the only local store on the island; however, this is not their natural diet and cannot sustain them throughout the year."

"As fears about the energy and environmental crises reach a fever pitch, we're all searching for solutions. And one possibility is that we could fix everything if we'd just shrink our population back down to about 2 billion people - which would put us roughly where we were at 80 years ago."

"Nature is at work. Character and destiny are her handiwork. She gives us love and hate, jealousy and reverence. All that is ours is the power to choose which impulse we shall follow."

"Then the immortal heart of the woods will beat against ours and its subtle life will steal into our veins and make us its own forever, so that no matter where we go or how widely we wander we shall yet be drawn back to the forest to find our most enduring kinship."