This project started with an apparently trivial discovery: Santiago Ramón y Cajal developed the law of dynamic polarization while living in the same building where Florentine Knives is located. While there are lots of pictures of him working, almost none of them shows a very important tool for his work: the knife. We don’t know the reasons for the concealment of the knife in those images but soon in the project we realised that cutting seemed a problematic action for some people; as Elaine Scarry states the weapon and the tool seem at moments indistinguishable. The relation with what is cut that determines the nature of the knife. We cut onions or chickens and sometimes we cut ourselves while doing so.