Personality (as I have said elsewhere) is the sum of our predilections along specific axes: gregarious or shy, brave or fearful, carefree or anxious. Character is what we make of these predilections. Sounds straightforward enough: you are born with a certain potential, and you, playing off your life’s circumstances, make yourself into a certain kind of person.
Of course, it isn’t straightforward at all. Part of the problem is that personality isn’t stable. It oscillates. Our predilections can alter, switch direction, and catch us by surprise. The alterations can happen after a long period of stability: I suppose midlife crisis, the sudden explosion of adolescent behavior in individuals old enough to know better, is a good example of this.
But small alterations happen on a weekly and daily basis. What used to be called manic depression, and is now termed bipolar disorder, is the pathological extreme of a normal human condition. We have moods, and they predicate our behavior.
An interesting question, not much considered, is the effect of moods on morality. In the grip of life-conquering moods, it seems to me, nothing can tempt or corrupt us. With middling moods, there’s a struggle. And there are low moods, moments of ineffable weakness, when one may well be particularly susceptible to moral failure: to drink excessively, say, or cheat on one’s spouse, or overcharge the company account.
The concept of character presupposes the ability to override our moods. It means resisting during low moments. That requires a great deal of self-knowledge, plus the formation of sturdy habits. The difficulty lies in the fact that moods color our judgment. We don’t feel changed: we feel the world (our jobs, our families, our futures, whatever) changing around us.
I suspect many terrible decisions are made by good people in the grip of atypical despair or panic or anger. At that point, they come to a consequential fork in the road. If they are truly good, they will face up to any failures and begin to rebuild. If failure is allowed to feed on itself — if one stoops to self-pity or rationalizations — the entire shape of a life can be warped forever, and mere mood will have shattered good character.