Tie You Up In Knots

I know my knots. I know every knot.
Though I may be old and blind, you can give me any rope and I can put any knot in it that you want me to put in it.
Hand me a rope with a knot in it, and I can tell you what kind it is in ten seconds.
This rope around my ankles, I know.
Same with the rope around my wrists.
The one around my neck is another matter, though. Give me a minute on that.
Pull on them all you want – all my secrets will die with me.