In addition to studying the humanities, the Aztecs were also great observers of the human body, with the tictil, or physicians, becoming quite accomplished herbalists who were encouraged to do research in the large gardens kept by the nobility.
One of the important works that sheds light on Aztec herbal practices is known as the Badianus Manuscript, a codex (or illustrated text) from 1552 that describes the use of over 180 plants and trees in the treatment of ailments.
Some treatments seem quite bizarre by today's standards. For example, the prescription for "pain or heat in the heart" included among its ingredients gold, turquoise, red coral and the burned heart of a stag, while a persistent headache could be cured by making a cut on the skull with a blade made from obsidian [source: Nicholson; Nguyen].
But other cures have since been held up by scientific research. A substance the Aztecs used as a painkiller called chicalote has been found to be Argemone mexicana -- a plant closely related to the opium poppy, which, of course has analgesic properties. The tictil also relied on the sap of the maguey (agave) plant as a disinfectant and wound treatment. It has since been shown that this sap can kill both Staphylococcus aureus and E. coli bacteria.