Folk medicine practitioners in 16th-century Europe left ingredients and fingerprints smudged on their manuals while developing remedies for minor ailments. Now, researchers are studying the chemical traces Renaissance people left behind to understand how they experimented with novel cures.

Two German medical manuals — "How to Cure and Expel All Afflictions and Illnesses of the Human Body" and "A Useful and Essential Little Book of Medicine for the Common Man" — were published in 1531 by eye doctor Bartholomäus Vogtherr. His systematically gathered recipe books for common ailments, like hair loss and bad breath, quickly became bestsellers in Renaissance domestic medicine.

A transcript of MLK's powerful speech.

I'll also today's Democracy Now! piece "MLK Day Special: Dr. Martin Luther King Jr. in His Own Words"

An excerpt from the beginning of the speech:

Now, let me make it clear in the beginning, that I see this war as an unjust, evil, and futile war. I preach to you today on the war in Vietnam because my conscience leaves me with no other choice. The time has come for America to hear the truth about this tragic war. In international conflicts, the truth is hard to come by because most nations are deceived about themselves. Rationalizations and the incessant search for scapegoats are the psychological cataracts that blind us to our sins. But the day has passed for superficial patriotism. He who lives with untruth lives in spiritual slavery. Freedom is still the bonus we receive for knowing the truth. "Ye shall know the truth," says Jesus, "and the truth shall set you free." Now, I've chosen to preach about the war in Vietnam because I agree with Dante, that the hottest places in hell are reserved for those who in a period of moral crisis maintain their neutrality. There comes a time when silence becomes betrayal.