SO DOES THE STONE is an entrance. Something like a mark on the ground. But let me tell you the story from the beginning: two months ago I met a Mexican poet at a party and I cannot stop thinking about her words. Maybe she is flirting with me, I thought at first, but now I wonder if she was warning me about the terrible threat that breathes underneath Philadelphia. I do not want to take a chance of misunderstanding her so I began to sign the city.