Corruptive

"The sensitive appetite is one generic power, and is called sensuality; but it is divided into two powers, which are species of the sensitive appetite---the irascible and the concupiscible. In order to make this clear, we must observe that in natural corruptible things there is needed an inclination not only to the acquisition of what is suitable and to the avoiding of what is harmful, but also to resistance against corruptive and contrary agencies which are a hindrance to the acquisition of what is suitable, and are productive of harm. For example, fire has a natural inclination, not only to rise from a lower position, which is unsuitable to it, towards a higher position which is suitable, but also to resist whatever destroys or hinders its action."