Well, one reason is that there are developmental disorders that seem to involve damage to one system but not to another.

一个原因是,发展障碍看上去,只会对某一个系统产生损害,而不会损害其他系统

耶鲁公开课 - 心理学导论课程节选

Psychology is not just the study of disease,weakness,and damage it also is the study of strength and virtue, Treatment is not just fixing what is wrong; it also is building what is right.

心理学不仅是对疾病，弱点和伤害进行研究,它也研究优点和美德，治疗不只是修复错误;,同时也要塑造正确的东西。

哈佛公开课 - 幸福课课程节选

Now, a virus is not capable of reproducing on its own, so if you got a virus into your body somehow and it didn't enter any of your cells, it would cause no damage because it could not reproduce.

病毒自身并不能繁殖,所以如果你的身体感染了病毒,而病毒没有进入细胞的话,因其不能繁殖所以不会对身体造成伤害

耶鲁公开课 - 生物医学工程探索课程节选