As noted earlier, a depressed mood can be defined phenomenologically by three central features: feeling depressed, experiencing a drop in self-esteem, and feeling more self-critical. The third component is somewhat synonymous with a drop in self-esteem but also reflects the self-slighting and self-disparagement that occurs during a depressed mood, and evokes Freud's famous description of the shadow of the super-ego falling on the ego. It helps to explain why people who refuse to accept any personal limitations and find blame or fault with other people (e. g. paranoid individuals) rarely, if ever, get depressed because things that go wrong are always someone else's fault, not their own.

People clearly vary in terms of their level of self-esteem, but whatever its baseline level, it drops further during a depressed state and, even more importantly, it is the degree to which it drops that defines the severity of depression.

What are self-esteem and self-worth? Like all straightforward concepts, they have an ineffable component when we seek to define them. Self-esteem can be global in that the individual may rate him- or herself similarly on a whole range of attributes, or ‘differentially’ across a range of parameters. Thus, some people may see themselves as very worthwhile in a work context but, as they do not have a lot of close friends, view themselves as unlovable.