Sentence:  According to the tradition, when an agent acts on a <WSD>patient</WSD>, the change is located in the <WSD>patient</WSD>. If the <WSD>patient</WSD> reacts on the agent, then the agent is a <WSD>patient</WSD> in the new relation. 
Meaning of the word marked with <WSD> tags:  One who, or that which, is passively affected; a passive recipient.