Something else that might derive from Lensman is the notion of relative "power levels" or "stages" of Jedi development/ability.
In the Lensman universe, most Lensmen are ordinary, "first stage" Lensmen. They have tremendous powers of mind, including the ability to use telepathy and to understand any language, but they are dependent upon their Lenses--the special crystals made by the Arisians--in order to use these techniques. A Lensman always wears his Lens upon his wrist, because without it he is powerless. However, in order to remove it without his consent, amputation of the limb is necessary.
Even the Unattached Lensmen--the "Gray Lensmen" who have been released from the hierarchy of the Galactic Patrol and are independent agents, following their own investigations as they see fit--are usually first-stage Lensmen.
Only a few Lensmen ever reach the "second stage" of mental discipline, and these few have been specially bred for it via Arisian eugenic lines. At this level, one gains the ability to control other people's bodies remotely, read unsuspecting minds, use the "sense of perception" to see perfectly without eyes, and even throw terrific mental bolts of force that can kill instantly. Notably, a Second Stage Lensman does not need to wear his Lens to use his mental power. (Even so, Kimball Kinnison feels compelled to wear it, as a mental amplifier of sorts, when confronting the tremendously powerful Gharlane of Eddore.)
The Second Stage powers are gained when a first-stage Lensman returns to Arisia for special training; however, most Lensmen are expressly forbidden from doing this. Kimball Kinnison, the male penultimate of the Arisians' human breeding program, is the first Lensman ever to return to Arisia and achieve the second stage. Later in the series, Clarissa MacDougall Kinnison, his wife (and the female human penultimate) becomes a Second-Stage Lensman as well. In addition, the three penultimate beings from the other Arisian breeding lines also reach this stage: Worsel of Velantia, Tregonsee of Rigel IV, and Nadreck of Palain VII.
Ultimately, the Arisians determine that the human genetic line offers the most potential for creating a third-stage intellect, the only thing which can destroy the Eddorians. Thus, Kim Kinnsion meets and marries Clarissa MacDougall, and their five children (one son, Christopher, and two sets of twin daughters) achieve the third stage.
Third-stage beings can actually generate their own Lenses out of thin air when necessary. They are also the only ones capable of knowing about the Eddorians, and understanding the true nature of the Arisians' grand design, without going insane. The five Kinnison children can unite their intellects into a single entity, the Unit, which gives them unprecedented strength of mind. Born outwardly human, the Children of the Lens are in fact practically immortal, and they possess powers beyond even the Arisians' knowledge.
So we have here a clear hierarchy of intellect "stages," from Stage One to Stage Three. The Arisians and Eddorians are somewhere around the Third Stage; but the Kinnison children surpass them all. Kimball Kinnison, main protagonist of the series, is a Second Stage intellect, but he can never reach the astonishing power his children will possess.
Now check out this quote from George Lucas, speaking to Leigh Brackett in the December 1977 ESB story conference sessions:
"Maybe we should set up some kind of levels of achievement. Ben can say that Luke is now a level 2 and Vader is a 4; 'I was a 6 and the Emperor is a 6, and he's on his way to becoming a 10, which will be a force so powerful in the universe that nothing can stop him. You must stop the Emperor before he achieves the level 10.' Luke has to destroy the Emperor. It does give us a time frame for the future--not only do they have to restore the Republic, but they also have to worry about the Emperor. We're really beginning to set up that situation."
Aside from the use of a 10-level Force power scale instead of a three-level Lensman scale, this is very similar to Doc Smith's conception of mental power levels. Here, though, Luke not only has to raise himself up as high as humanly possible, like the Children of the Lens, but he also has to prevent the Emperor from doing the very same thing.