Because I've jotted down so many quotes in so many places now that I'm kind of losing track, and I really like how transcribing them in a more personal/permanent way makes me slow down for 20 minutes and vaguely reflect on something outside of what I'm actually doing.
After looking into where this one originated, it seems that the people of today have altered it slightly, but it doesn't matter because the idea is just beautiful. What he actually writes in The Tell-Tale Heart and Other Writings is this:
“And have I not told you that what you mistake for madness is but over-acuteness of the sense? --now, I say, there came to my ears a low, dull, quick sound, such as a watch makes when enveloped in cotton. I knew that sound well, too. It was the beating of the old man's heart. It increased my fury, as the beating of a drum stimulates the soldier into courage.”
It's a start.