The head illustration is by Thomas Bartholin, 17th century, found at Wikipedia Commons [link]
If you wonder how I got the idea remember these lyrics from The Pixies:
With your feet in the air and your head on the ground Try this trick and spin it, yeah Your head will collapse But there's nothing in it And you'll ask yourself
Where is my mind
And if you even want to know why it is this sentence got stuck in my mind (whereever it might be right now) I'm afraid you'll have to read my latest journal entries.