How can we be sure that our interpretation of anything is close enough to that which is experienced by another? How can we be sure that there even are other people? If all of our neural impulses are prompted by nothing more than electrical signals from our nervous system, then we are each of us living inside our own heads. Each of us is experiencing their own virtual reality and no doubt colouring it with the emotional or experiential baggage that defines us. When considered thus, we can actually make the astonishing claim that there is no such thing as one absolute definition of reality. Indeed the very reality that we experience can never be truly shared, because the sharing must take place via our nervous systems.