In a closed system, during a reaction, nothing is lost, nothing is created. All changes. This is what I've learned in chemistry in the old good times of school. These days will never come back again. We were discussing last time, in a restaurant, with my friends, the concept of plastic surgery. And how plastic surgeons do the liposuction to the thigh or hip and add the fat generated to other parts of the body like the cheek or lips. This process goes perfectly with the Law of conservation of mass of Lavoisier, in chemistry, which basically states that mass cannot be created or destroyed, but can change its form. What do you think? And let's make this topic broader. What do you think of plastic surgery in general?