THE MIRROR
The most influential invention in the past 2000 years has been the mirror: It has shown to each person how she or he appears to other persons on the planet. Before the widespread production and use of mirrors that came about in the Renaissance, humans could mirror themselves in lakes and metallic surfaces. But only with the installation of mirrors in everyday life did viewing oneself from the outside become a daily habit. This coincided with the advent of manners for eating, clothing and behaving. This again made possible the modern version of self-consciousness: Viewing oneself through the eyes of others, rather than just from the inside or through the eyes of God.
Hence, consciousness as we know it is an effect of an advanced mental task: To acknowledge the person experienced out there in the mirror as the same as the one being simultaneously experienced from within. To know that the person out there in the mirror is controlled by me in here. The invention of the mirror is closely related to the problem of free will and to the invention of the modern human ego as described in this poll by Jaron Lanier.
The problem with overemphasis of conscious control is thus the problem of supervising oneself through the eyes of others, rather than just acting out. Many malaises of modern life stems from the fact that one tends to consider the mirror-image of oneself as more real than the view from within.
This new loop of the-outside-person-viewed-by-the-inside-person recently got a parallel with the first images of the Earth seen on the sky of the Moon: No longer just the planet we can touch and live on, the Earth became a heavenly body comparable to other celestial objects.