Eye of Harmony
The Eye of Harmony (also known as Rassilon's Star, was a power use utilized by the Time Lords.
Legend
According to The Book of the Old Time Rassilon "with a great fleet", found the Eye of Harmony in a "black void" and returned it to Gallifrey at which "the people rejoiced". (DW: The Deadly Assasin)
In the Panopticon
The Eye of Harmony lay under the floor in the center of the Panopticon. (DW: The Deadly Assasin)
The Rod and the Sash of Rassilon
Unknown to most Time Lords and even the Lord Presidents themselves, the ancient artefacts ceremonially given to the Lord Presidents had a practical function. (DW: The Deadly Assasin)
The Rod of Rassilon, opened the floor of the Panopticon like a key, allowing a black hexagonal oblelisk to rise from the floor which contained the Eye of Harmony itself. (DW: The Deadly Assasin)
The Sash of Rassilon, also given to the President, supposedly served as means of protecting the wearer against the forces of the black hole. The practical functions of the Rod and the Sash and the true nature of the Eye of Harmony remained unknown to most on Gallifrey. (DW: The Deadly Assasin)
Attempt to open the Eye
The Doctor deduced the true use of the artefacts by interpreting enigmatic passages from The Book of the Old Time. He also realized that the name Eye of Harmony symoblically described a black hole contained and balanced against the mass of the planet Gallifrey by Rassilon's engineering. The Master had also, separately come to the same conclusions. He believed, probably incorrectly, that the Sash of Rassilon would give him immunity against the forces unleashed by the Eye if opened. If it had opened, the Eye of Harmony would have functioned as a normal black hole and destroyed Gallifrey. (DW: The Deadly Assasin).
- Omega had also utilized a black hole in order to enable the Gallifreyans to acquire the power of time travel.
Inside the Doctor's TARDIS
It also seems that the Eye of Harmony existed within the Doctor's TARDIS during the later part of his seventh and eighth incarnation and powered it. The particular structure of a Human eye had the effect of opening it. If opened partially, the Eye gave visions of the past. (DW: Doctor Who: The TV Movie)
- With the later destruction of Gallifrey, the Eye of Harmony in the TARDIS presumably no longer served as a source of power.
Note
No on-screen explanation of how the Eye of Harmony could exist in two places at once exists onscreen. The popular fan explanation states that each TARDIS had a link to the actual Eye of Harmony. The BBC official guide to the old Doctor Who series and the TV Movie confirms this, and says that following the duestruction of Gallifrey, the Doctor's TARDIS now powers itself with the energy from time rifts.
