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

And penis envy is an account of a developmental state that every one of you who is female has gone through, according to Freud.

根据弗洛伊德的理论,阴茎嫉妒是对女性所经历的，某一发展状态的解释。

耶鲁公开课 - 心理学导论课程节选

They seem to be going somewhere and there's this sort of force of pull or gravity in music having to do with some chords wanting to go to other chords.

和弦向某一个方向发展，就像有一股力量拉着它们,或者说音乐的重力吸引着它们，让一些和弦想行进成为另一些和弦。

耶鲁公开课 - 聆听音乐课程节选