For most of the history of the world, heat was a fact of life.
Cavemen and cavewomen made do in the summer just the way billions of people in underdeveloped countries still do:
They sweated, they fanned themselves, they sought shade.
Heat made beaches popular.
Heat gave us Marilyn Monroe catching the breeze from the subway passing beneath her.
Heat gave us Popsicles.
And iced tea. And tank tops. And flip-flops.
Eventually Willis Carrier's invention, air conditioning, spread from luxury hotels and movie theaters to individual homes.
And most everybody figured out how to stay cool.
Carrier gave us the swamp-turned-theme park called Florida and the population explosion in the previously too-steamy South.
He gave us air-conditioned cars that keep us from overheating during the trip from our air-conditioned homes to our air-conditioned workplaces.
The recent storms that knocked out power around St. Louis for a number of hot days underscored how dependent most of us have become on air conditioning.
When the heat wave that rolled over the country last week finally left, 90-degree temperatures felt like relief.
Now that many of us live air-conditioned lives almost 24 hours a day, outdoor temperatures nearing triple digits seem all the more extreme.