"Lower and deeper to the real masses" originates from Lenin's "Imperialism and the Split in Socialism"
Neither we nor anyone else can calculate precisely what portion of the proletariat is following and will follow the social-chauvinists and opportunists. This will be revealed only by the struggle, it will be definitely decided only by the socialist revolution. But we know for certain that the “defenders of the fatherland” in the imperialist war representonly a minority. And it is therefore our duty, if we wish to remain socialists to go down lower and deeper, to the real masses; this is the whole meaning and the whole purport of the struggle against opportunism. By exposing the fact that the opportunists and social-chauvinists are in reality betraying and selling the interests of the masses, that they are defending the temporary privileges of a minority of the workers, that they are the vehicles of bourgeois ideas and influences, that they are really allies and agents of the bourgeoisie, we teach the masses to appreciate their true political interests, to fight for socialism and for the revolution through all the long and painful vicissitudes of imperialist wars and imperialist armistices.[1]