I love this lesson! Of all the Harry Potter characters, I've always identified most with Severus Snape. Many people often dismiss the character as a Death Eater and little more than a bully to innocent children, but they've never experienced a life focused on guilt and unresolved grief towards the only person they ever truly loved. Grief and attachment issues are a theme in Slytherin, to a large extent. The Bloody Baron took the life of the women he loved for not sharing his feelings. Merope Gaunt drugged the man she was attracted to, and when she stopped giving him the potion and he wasn't interested in her, she died in childbirth, completely heartbroken. Tom Riddle was said to not have the ability to love at all. I suspect many Slytherin marriages are arranged. There are exceptions, such as Andromeda Tonks, and I think there's hope for Harry Potter's generation, though.
My past isn't anywhere near as dark as Snape's, fortunately, but I have experienced an abnormally huge number of deaths. Much of my childhood was spent attending funerals. My grandmother had 4 daughters, and all 4 became pregnant the same year. I was born February 12, on a Thursday. The very next day, Friday the 13th, her husband died in a fire while she was at the hospital. In March, one cousin was born, and he died when he was 12, in a freak accident. Another cousin was born in August, and she died young of internal bleeding. The fourth cousin was born in September, and he died young as well, in a house fire. My own father died unexpectedly when I myself was 12. And this just scratches the surface.
Although this quote did not originate with her, it's still relevant, and one of my favorites. As Queen Elizabeth II said when Princess Diana died,
Grief is the price we pay for love.
Love and grief are two sides of the same coin. If you don't love, you won't grieve. I continue to love, even though the grief is overwhelming. I think Snape stopped loving and focused all of his energies on trying to take action because of the death of Lily Potter. He blamed himself. Because of his unresolved grief and his guilt, he shut down his feelings and never allowed himself to be hurt again, which meant he never cared deeply for anyone else again, and this meant he lost much of his empathy. He couldn't relate to the pain he was causing his bullied students.