23 At the same time, the various forms of aid supplied at present to the sacred missions are everywhere &r short of the amount required for a satisfactory prosecution of missionary effort. This insufficiency of means, which, unfortunately, is not confined to Africa, seems to affect this continent more seriously than other missionary fields on account of Africa's peculiar situation at the present moment. For this reason, We deem it opportune, Venerable Brethren, to go into some detail with regard to the problems that are met in Africa.
Source: Fidei Donum (Vatican.va)