By Isidro Aguirre
The “guardia vieja” is the era between 1875/80 up to 1917/1925, in which traditional tango was created.
In this time lapse, the 2×4 tango appeared (2 whole notes per compass in the music scale) and it involves the dance (choreographic version), the music (melody and others) and the poetry (lines).
Its diffusion and consumption -since the XXth century- is obvious
through its recordings and its social validation catalyzed its
development and exportation, since its consecration in Paris.
 We do not limit it to the color of skin nor a brothel thing, nor marginal or immoral, as it has been said several times. It was enjoyed through all social classes and nationalities that lived in porteñan ground.
 This is the best definition that we found, belonging to page 65 of Hugo Lamas and Enrique Binda in their book “El tango en la sociedad porteña 1880-1920”, Editorial Héctor L. Lucci, Buenos Aires (1998).
 In 1902 the first lyrical tango appeared “La bicicleta” from Angel Gregorio Villoldo, recorded by Eloisa Ceballos.