By its very nature, the dark side invites rivalry and strife. This is the greatest strength of the Sith: it culls the weak from our order.
The constant battling of the Sith since the beginning of recorded history served a necessary purpose: it kept the power of the dark side concentrated in a few powerful individuals. The Brotherhood had changed all that. There were now a hundred or more Dark Lords following Kaan, but most were weak and inferior. The Sith numbers were greater than they had ever been, yet they were still losing the war against the Jedi.
The power of the dark side cannot be dispersed among the masses. It must be concentrated in the few who are worthy of the honor.
The strength of numbers was a trap . . . one that had snared all the great Sith Lords who had come before. Naga Sadow, Exar Kun, Darth Revan: each had been powerful. Each had drawn disciples in, teaching them the ways of the dark side. Each had assembled an army of followers and unleashed them against the Jedi. Yet in each and every case the servants of light had prevailed.
The Jedi would always remain united in their cause. The Sith would always be brought low by infighting and betrayals. The very traits that drove them to individual greatness and glory-the unrelenting ambition, the insatiable hunger for power-would ultimately doom them as a whole. This was the inescapable paradox of the Sith.
Kaan had tried to solve the problem by making everyone equal in the Brotherhood. But his solution was flawed. It showed no understanding of the real problem. No understanding of the true nature of the dark side.
The Sith must be ruled by a single leader: the very embodiment of the strength and power of the dark side. If all are equal, then none is strong. Yet whoever rose from the swollen and bloated ranks of the Sith to claim the mantle of Dark Lord would never be able to hold it. In time the apprentices will unite their strength and overthrow the Master. It is inevitable. Together the weak would overwhelm the strong in a gross perversion of the natural order.
. . . .
Minions and servants could be drawn in to the service of the dark side by the temptation of power. They could be given small tastes of what it offered, as an owner might share morsels from the table with his faithful curs. In the end, however, there could be only one true Sith Master. And to serve this Master, there could be only one true apprentice. Two there should be; no more, no less. One to embody the power, the other to crave it. The Rule of Two