I love Mark Twain! I also hate the muck and mire of depression, like thick, deep mud that tries to suck you down with each difficult and exhausting step. I am sorry to hear you're having a tough time. I know those feelings all to well. Did something happen, that you're aware of, to trigger this depression? Usually there is a trigger somewhere. Not always, but usually. Give it some thought. Sometimes, I discover something that seemed benign at first, has really dragged me down and putting my finger on it helps me a lot. I hope you get through this soon!