"Comrades, the question of the relationship between the Communist International and the trades unions is the most serious, most important question facing our movement. The trades unions are the biggest mass organisations of the working class; they play a decisive role in the economic struggles, the chief elements in the disintegration of capital, and after the victory of the revolution the trades unions will be in the forefront of those organisations called on to work at the economic construction of socialism."
January 1, 1970
https://en.wikiquote.org/wiki/Karl_Radek