The human mind, on the other hand, may respond to a set of circumstances in an infinite number of ways. Science's goal is to tease out the neural pathways down which depression gathers its forces, then invent medicines capable of treating individual patients -- regardless of how their experiences may have shaped their illness. This is an immensely difficult task, among the most difficult humans have ever faced.

As she is sure to note, the swirling of uncertainty and reclusiveness that often surround those who suffer from depression, especially severe derpessive disorder, only add to the difficulties of treatment.
Living through Jeff's depression, I came to understand how cruelly our society treats people with mental illness. "If I had cancer," Jeff said at one point, "people would be asking me how I'm doing, instead of acting like I'm a jerk."