Lumet almost disappears in this movie, it's like it doesn't need to be directed. The key is the screenplay and the casting. And Network benefited from both in big ways.
There are some differences: the setting for this part of it was—as one can read in the screenplay—an auditorium, one of those theater-prosceniums set up for presentations and dog-and-pony shows, that spend most of their time fallow and unused, a waste of architecture and space, merely ego-rooms.
But, Lumet stages it in a board-room, with their elegant long tables of rectangular shape that ensure the power-seat is at one end (as opposed to round-tables where all chairs have equal prominence). And it is from there that Arthur Jensen thunders his sermon to the proselyte Howard Beale. It is at once a dressing down of Beale's power by showing him a higher one, but also an acknowledgment of that power by bestowing a Crusade upon him, taking the gospel of personal freedom away and bestowing on him an new interpretation where freedom's just another word for disposable income.
This world-view is probably true to those who have never had to drive a car or buy their own groceries or cook their own food or play with their own children. All they have to think about is throwing their lightning bolts rather than the effect it might have on the populace from whom they expect their fealty or tithing. Why should a God have to worry about that?
Anyway...have you slaughtered a goat to Zeus lately? I thought not.
The Set-Up: UBS anchorman Howard Beale (Peter Finch) has gone insane. Threatened with being fired for poor ratings, he announced that he would kill himself on-air for his last broadcast, cynically thinking it would boost his ratings. It worked without firing a shot. The perversity factor increases viewership and Beale goes off the deep end, ranting about the vagaries of the world on his show before collapsing in a fevered heap. Rather than take him off the air, the new format is exploited, making "The Howard Beale Show" the number one news program in America. But, Beale's persecutional rants are going a little bit anti-rich, anti-capitalism for the network's CEO Arthur Jensen (Ned Beatty), who wants to see Beale in his office.
Action.
151. INT. ARTHUR JENSEN'S OFFICE
An enormous office with two walls of windows towering over the Manhattan landscape and through which SUNLIGHT streams in.
ARTHUR JENSEN is rising from behind his massive desk --
JENSEN Good afternoon, Mr. Beale. They tell me you're a madman.
CAMERA DOLLIES to include HOWARD just coming into the room.
HOWARD(closing the door behind himself) Only desultorily.
JENSEN How are you now?
HOWARD (as mad as a hatter) I'm as mad as a hatter.
JENSEN Who isn't?
JENSEN Don't sit down. I'm taking you to our conference room which seems more seemly a setting for what I have to say to you.
He takes HOWARD'S arm and moves him to a large oaken
door leading out of JENSEN'S office --
JENSEN I started as a salesman, Mr. Beale. I sold sewing machines and automobile parts, hair brushes and electronic equipment.
JENSEN They say I can sell anything.
JENSEN I'd like to try and sell something to you --
They pass into --
152. INT. THE CONFERENCE ROOM - C.C. AND A. BUILDING
The overwhelming cathedral of a conference room
remembered perhaps from an earlier scene where Frank
Hackett gave his annual report. When last seen, it was
in pitch darkness, but now the enormous curtains are up,
and an almost celestial light pours in through the huge
windows. Being on the 43rd and 44th floors, the sky
outside is only sporadically interrupted by the towers
of other skyscrapers. The double semi- circular bank of
seats are all empty, and the general effect is one of
hushed vastness --
JENSEN Valhalla, Mr. Beale, please sit down --
He leads HOWARD down the steps to the floor level, himself ascends again to the small stage and the podium.
JENSEN suddenly wheels to his audience of one and roars out:
JENSEN You have meddled with the primal forces of nature, Mr. Beale, and I won't have it,
JENSEN ...is that clear?!
JENSEN You think you have merely stopped a business deal -- that is not the case! The Arabs have taken billions of dollars out of this country, and now they must put it back.
JENSEN It is ebb and flow, tidal gravity, it is ecological balance!
JENSEN You are an old man who thinks in terms of nations and peoples.
JENSEN There are no nations! There are no peoples! There are no
Russians. There are no Arabs! There are no third worlds! There is
(pause)
JENSEN Because you're on television, dummy. Sixty million people...
JENSEN ...watch you every night of the week, Monday through Friday.
HOWARD slowly rises from the blackness of his seat so that he is lit only by the ethereal diffusion of light shooting out from the rear of the room. He stares at JENSEN spotted on the podium, transfixed.
HOWARD I have seen the face of God!
In b.g., up on the podium, JENSEN considers this curious statement for a moment.
JENSEN You just might be right, Mr. Beale.
Network
Words by Paddy Chayevsky
Pictures by Owen Roizman and Sidney Lumet
151. INT. ARTHUR JENSEN'S OFFICE
CAMERA DOLLIES to include HOWARD just coming into the room.
HOWARD(closing the door behind himself) Only desultorily.
HOWARD (as mad as a hatter) I'm as mad as a hatter.
He takes HOWARD'S arm and moves him to a large oaken
door leading out of JENSEN'S office --
They pass into --
152. INT. THE CONFERENCE ROOM - C.C. AND A. BUILDING
The overwhelming cathedral of a conference room
remembered perhaps from an earlier scene where Frank
Hackett gave his annual report. When last seen, it was
in pitch darkness, but now the enormous curtains are up,
and an almost celestial light pours in through the huge
windows. Being on the 43rd and 44th floors, the sky
outside is only sporadically interrupted by the towers
of other skyscrapers. The double semi- circular bank of
seats are all empty, and the general effect is one of
hushed vastness --
HOWARD sits in one of the 200 odd seats.
JENSEN pushes a button, and the enormous drapes slowly fall, slicing
away layers of light until the vast room is utterly dark. 
Then, the little pinspots at each of the desks, including the one behind which HOWARD is seated, pop on, creating a miniature Milky Way effect.
A shaft of white LIGHT shoots out from the rear of the room, spotting JENSEN on the podium, a sun of its own little galaxy.
Behind him, the shadowed white of the lecture screen.JENSEN suddenly wheels to his audience of one and roars out:
Russians. There are no Arabs! There are no third worlds! There is
no West!
JENSEN There is only one holistic system of systems, one vast and
immane, interwoven, interacting, multi-variate, multi-national dominion of dollars!
JENSEN Petro-dollars, electro-dollars, multi-dollars!,
Reichmarks, rubles, rin, pounds and shekels!
JENSEN It is the international system of currency that determines the totality of life on this planet!
JENSEN That is the natural order of things today, Mr. Beale!
JENSEN That is the atomic, subatomic and galactic structure of things today!
JENSEN And you have meddled with the primal forces of nature...
JENSEN ...and you will atone!
JENSEN Am I getting through to you, Mr. Beale?
JENSEN You get up on your little twenty-one inch screen, and howl about America and democracy. There is no America. There is no democracy. There is only IBM and ITT and A T and T and Dupont, Dow, Union Carbide and Exxon. Those are the nations of the world today.
JENSEN What do you think the Russians talk about in their councils of state --
JENSEN Karl Marx? They pull out their linear programming charts, statistical decision theories and minimax solutions and compute the price-cost probabilities of their transactions and investments just like we do.
JENSEN We no longer live in a world of nations and ideologies...
JENSEN ...Mr. Beale. The world is a college of corporations, inexorably deter- mined by the immutable by-laws of business.
JENSEN The world is a business, Mr. Beale!
JENSEN It has been...
JENSEN ...since man crawled out of the slime, and our children, Mr. Beale, will live to see that perfect world...
JENSEN ...in which there is no war and famine, oppression and brutality --one vast and ecumenical holding company...
JENSEN ...for whom all men will work to serve a common profit, in which all men will hold a share of stock,
JENSEN ...all necessities provided, all anxieties tranquilized, all boredom amused.
JENSEN And I have chosen...
JENSEN ...you to preach this evangel, Mr. Beale.
HOWARD (humble whisper) Why me?
HOWARD slowly rises from the blackness of his seat so that he is lit only by the ethereal diffusion of light shooting out from the rear of the room. He stares at JENSEN spotted on the podium, transfixed.
In b.g., up on the podium, JENSEN considers this curious statement for a moment.
Network
Words by Paddy Chayevsky
Pictures by Owen Roizman and Sidney Lumet
Network is available on DVD and Blu-Ray from M-G-M Studios.