Being is a substance.
The universe is composed of Being. Human beings are concentrated forms of that expression of Being, and man's Being-duty, an idea Gurdjieff introduced, is founded on the principle that a man must concentrate his Being in such a way as to express sacred functions.
We could conduct long discussions about how one ought to go about achieving that; and everyone does. Inner works are rife with opinions on the matter, many of them (distressingly, and unconciously) ego-driven. Yet it seems to me that the reason one ought to fulfill one's Being-duty is not often discussed.
Why should we do such a thing? Because Gurdjieff says so? Or even, "just because?"
On our level, the whole aim of inner work is to mediate the flow of the Divine Being into life. This is the essential action of Being-duty. One can construct other, more selfish aims, but real service always consists of this effort to become transparent enough that the Divine Principle can arrive from a higher level, flow inward into the essence of Being, and then be radiated outward — without manipulation—into the surrounding environment.
Man or woman, in other words, receives sacred impulses or energies, and then emantes them, without interfering. This, at any rate, is how things ought to be arranged. Alas! Nothing of the kind takes place, and our true purpose in being here is thwarted. Yet the purpose cannot and does not change, no matter how many layers of philosophy or self-interest mankind applies to it.
This task in life ought to be the absorbtion and concentration of an energy that is composed, above all, of Love; and that energy ought, after concentration in the abdomen, the heart, and the other essential centers or chakras, be radiated outward naturally, without the contamination of ego or personality. To become open, as Gurdjieffians call it, would be to become open to Love; there is no other principle, and there is no other inner work, because this is what Reality is made from and founded on. Any action that fails to emanate from Love already comes from a lower place, and there are an endless number of them in us.
Be very wary of those who claim to work, but are not loving. Measure each condition in yourself and others according to this question, and attend. There is much to be learned in this exercise, and you may be shocked if you conduct it with real attention. There are many, many liars out there, and in us, and they run most of the show; yet none of them can stand even a single instant of the Light of Love, if it is turned on them.
So this is Being-duty; to Love. Either self-remembering begins here, grounded in Love, or it does not begin at all.
May your soul be filled with light.