He became notable by his contributions to the philosophy of body culture and by his political radical writings on folk and nation.
Sociologists have placed Eichberg's "materialistic phenomenology" at the intersection of Norbert Elias, Michel Foucault, and the Frankfurt School of Critical Theory.
In his youth, Eichberg engaged on the radical right wing, contributing from 1961 currently to the neo-fascist monthly Nation Europa.
Renouncing from the conservative and anti-democratic "Old Right", Eichberg and the National Revolutionaries referred to anti-Nazi intellectuals of the Weimar Republic like Ernst Niekisch, Karl Otto Paetel de:Karl Otto Paetel and A. Paul Weber de:A. Paul Weber as well as to the anti-Hitler resistance of 20 July 1944.
Entering into discussions with the New Left, he commented: "National is revolutionary" and "Who does not want to talk about the peoples, should silence about the human being".
Eichberg's contributions about national identity and the "Balkanization of everyone" were now published by periodicals from socialist, anti-authoritarian, and anarchist milieus.
Eichberg was especially active in the milieu of Danish People's Academies (folke-højskoler), which relate themselves to the democratic revival of 1848 and the romantic populism (→romantic nationalism) of the poet N. F. S. Grundtvig.
At the 60th anniversary of Eichberg, a Danish festschrift was published collecting critical contributions about "folk" and the "people".
Eichberg was said to act as "godfather" for a certain anti-American and anti-capitalist left wing - German Social Democrats (SPD), Socialists and Greens -, who followed a hidden right-wing, nationalist agenda.
The Conservative minister of culture, Brian Mikkelsen, deprived the institute in 2003 of public funding, which it had received during 25 years, and entered into a sharp debate with Eichberg in the media.