There are, at base, only two fundamental questions to be answered concerning the actions of man. These are :
What must we do to live?(The latter first identified by A. Rand)
And this "latter" is the specific task of the luminary. To shine the light of the totality his experience (as slave, drone, human being) on that which is conducive to the maintenance of life. It is his job to say "You have done well. Now do this." He is the center point against which all others take their reference. Without such reference all the "tug boats" drift away individually, unable to pull in concordance.
A luminary observes all ... bears witness to existence ... contemplates philosophical matters ... resolves quandaries caused by government irrationality ... makes new corporate contacts (golf, power lunch) ... and in general is just there. Therefore, since his position is not one of "work" in the commonly understood sense, he is often thought to be superfluous. Nothing could be further from the truth which is why the species survives and "doth thrive".
There is a gradientThere is no smooth transition between these three levels.
Those in the slave ranks may occasionally do head work but almost never became the inspiration to others.
Luminaries seldom (if ever) do manual labor but often do the work of the drone ... specifically the major details not the minor.
Middle managers have the worst of it. They must do all to some extent on some occasions. And in their attempts to please everyone ... please no one ... then they have a heart attack and die ... thus leaving less competition for the luminary position of which there are few.