Quod apostolici muneris is the second encyclical of Pope Leo XIII. It was published on 28 December 1878. The encyclical opposes "socialism, communism and nihilism", regarded as three aspects of a single ideology that is opposed to moral values, natural institutions and the principles of authority and property. This is contrasted with the Church's own social theory which respects social distinctions while stressing the importance of helping the poor. This was not a new battle for the Pope. He was continuing the war which had been waged for years against these enemies of the Catholic Faith beginning with Pope Clement XII (1730-1740).