At this point I spend more money on audiobooks than I spend on print books (although that's in part because loved ones send me print books as gifts (thanks, loved ones!)) and it adds up fast. For me, it's worth it, but the hefty price of audiobooks makes it hard for a newcomer to try things out, especially when there's so much free audio available online. Why pay for the professionals? Again, for me, the professionals earn their keep, but I can easily see why this is a hard case to make.

So it's very smart of Audible.com to hold these holiday and summer sales. The one going on now is a doozy: a list of "summer paperbacks" (which I assume means the audio versions of books that, in print, are paperbacks) for only $5.95 each.

I just grabbed these, all unabridged:

• Our First Revolution: The Remarkable British Upheaval That Inspired America's Founding Fathers by Michael Barone
• How to Survive a Robot Uprising: Tips on Defending Yourself Against the Coming Rebellion
  by Daniel H. Wilson
• The Politically Incorrect Guide to Capitalism by (yes, our very own) Dr. Robert P. Murphy

The only reason The Whiskey Rebellion by William Hogeland isn't also on that list is because I already own it.

Here are the on-sale titles I didn't buy but do recommend:

• 2001: A Space Odyssey by Arthur C. Clark
• Fahrenheit 451 by Ray Bradbury
• The Great Gatsby by F. Scott Fitzgerald

Another on-sale title that I already own and listened to only last spring is The Demon Under the Microscope: From Battlefield Hospitals to Nazi Labs, One Doctor's Heroic Search for the World's First Miracle Drug by Thomas Hager.

It is a fascinating and little-known tale about the first false steps and real advances that took us from an age of epidemics and common childhood death and crippling disease to a medical era of inoculations, antibiotics, and surging survival rates. It does have an unbelievably naive chapter about the heroic government finally gaining the power to reign in and regulate the evil capitalists, but you can fast-forward through that section. The rest of the book is unexpectedly engrossing.

I'm embarrassed by how little of this I knew and how much of our current condition I'd taken for granted. Less than 100 years ago, the rich and powerful shared with the poor and marginalized the likelihood of seeing at least one of their children (or the mother, giving birth do those children) die from the sort of disease and infection we barely think about today. Millennia of disease followed by less than a century of pharmaceuticals.

My whole family took turns being miserably sick last week from a mysterious infection, so this topic hits home right now. After listening to The Demon Under the Microscope, I'm more grateful than ever to have been born in the 20th century and to still be alive in the 21st.