If you are human, and honest, you will likely have to admit that you've glimpsed your own heart and noted a depth of darkness there. Perhaps you have viewed it with some horror.
I know I have.
In sad and dark moments such as those, I know I am capable of horrific things. Things we think only monsters are capable of. Things we don't believe are good, or redemptive, or even a part of our character.
And if you are fortunate, as I am, you will be met with compassion and concern in those moments. As though perched on a precipice with condemnation on one side and waves of mercy on the other, with the ever present possibility of flipping from one side full on into the other.
Staring into one's own ugliness can provide the arena for more honest self evaluation. A change in direction. Additional safe-guarding against allowing that darkness to inhabit more space, caging it from future release.
It's wise to recognize what we ourselves are not above becoming.