Like Lucy, the Australopithecus from which all humans spawn, this brownie recipe from “The Joy of Cooking” is the point of origin for all brownies:

In a double boiler, melt
½-cup butter
4 oz. Unsweetened chocolate
Let this cool.
Beat together until light and foamy
4 eggs
½ tsp. Salt
Gradually add
2 cups sugar
1 tsp. Vanilla
While still beating
With a few swift strokes combine the cooled chocolate mixture into the eggs and sugar. Even if you normally use an electric mixer, do this part manually. Before the mixture becomes uniformly colored, stir in gently,
1 cup sifted all-purpose flower
Nuts are optional, but I feel they get in the way of the sugar fix.
Bake at 350°F, in a 9x13 inch pan for about 25 minutes. Cut when cool.

From the 1932 edition of  The Joy of Cooking
Laraine Newman