El Orinoco ilustrado y defendido. Historia natural, civil y geográfica de este gran río y de sus caudalosas vertientes, govierno, usos, y costumbres de los indios sus habitadores, con nuevas, y utiles noticias de animales, arboles, frutos, aceytes, resinas, yervas, y raices medicinales ...

Inspired by the success of Acosta’s Natural History, Gumilla wrote lush descriptions of native life along the Orinoco River in Venezuela and Colombia. His characterization of local healing practices was informative, but critical of technique. Digital facsimile of the much corrected 1791 edition from the Internet Archive at this link.