Erasmus Darwin

“ The Materia Medica includes all those substances, which may contribute to the restoration of health. These may be conveniently distributed under seven articles according to the diversity of their operations.
1. Nutrientia, or those things which preserve in their natural state the due exertions of all the irritative motions.
2. Incitantia, or those things which increase the exertions of all the irritative motions.
3. Secernentia, or those things which increase the irritative motions, which constitute secretion. ”