For our third journey, we find out what changes nano particles can bring to our body. We discover new nanomedical treatments. Spectacular applications are already in use, notably in the field of oncology. We will also observe new molecular diagnostic tools. They allow crucial medical analyses to be done in a “lab” no bigger than a credit card. But it is reconstructive medicine that most vividly shows us the astonishing horizons that this knowledge of living things can bring: if newts can regenerate severed limbs, why not us? The initial results are already in, with mice regaining sight after their optic nerve was cut!