The Summary of Physics Restored

230This discord of the principles has either an inward, radical cause, such as defective seed, faulty generation or old age, or an external, accidental cause, such as excessive fullness or depletion, from which arise excess or deficiency in the humours and spirits. It may also arise from putrefaction, deadly poison, wasting, grief, injury or some obstruction inflicted upon the organs of life, and similar things that do violence to Nature.