Gomez goes well beyond the basic parameters of the Mansa Musa story to seek its deeper meaning. Mali was playing sophisticated geopolitics, he argues, bidding for recognition by the Mamluks as a peer in the Islamic world, and perhaps looking for a buffer against the kind of aggression that Sudanic Africa had periodically suffered at the hands of the Islamic Amazigh, or Berber, kingdoms of North Africa, whose Marinid Empire then stretched deep into Iberia. Gomez speculates that the grand geopolitical gambits of Abu Bakr and Mansa Musa shared similar motives: both were looking for a way for Mali to escape the threatening political interference and costly economic control of the Berber middlemen of North Africa through whose territory their gold passed on its way to Europe and elsewhere.
One of its great strengths is that it reveals the often surprising success that Africans had throughout the first four hundred years of their encounter with Europe. Early in his book, Green makes a general observation about the effects Europeans had on African politics when they began trading in West Africa in the fifteenth century. Big, sophisticated states like Songhai, the empire that succeeded Mali, were weakened and eventually broke up, while smaller ones, including many petty kingdoms, became autonomous and were strengthened by economic exchanges with the newcomers.
An Ecumenical Problem The question of the two kingdoms is one of the most pressing and delicate in contemporary religious and theological thought. No other aspect of Luther's theology has been so fiercely attacked as this doctrine. Where Luther drew a clear line between spiritual and temporal authority, and expressly emphasised that under no circumstances should these two realms be confused, this has been interpreted as if he had thereby opened the door to the secularisation of society and given a completely free hand to the State. Some critics have gone so far as to see in this doctrine the ultimate root of the National Socialist ideology, while even a theologian like Karl Barth has sharply criticised Luther from a similar point of view.
 This criticism directed from various quarters against Luther's doctrine of the two kingdoms has gained a hearing in many circles. The following statement, which appeared recently in a church paper in Norway, is typical of a fairly widespread conception:
 Anyone with the least grasp of the problem will recognise that this conception, at any rate as given in the popularised version quoted above, is a total distortion of Luther's actual doctrine. The whole point of his doctrine of the two kingdoms was in fact to prevent the powers of this world from encroaching on the realm of conscience. In his pamphlet On Worldly Authority, he wrote:
 If it were only a question of refuting criticism from without, mainly determined by the political situation, there would be little point in dealing at length with this matter. Another factor, however, enters into it. Luther's doctrine of the two kingdoms has assumed a rather controversial position in ecumenical debate, and has in many circles become a stumbling-block. It is easy to see the reason for this. It is an essential part of the work of the ecumenical movement to strengthen the social witness of the Church in the confused situation of contemporary society. But does not Luther's sharp line of demarcation between spiritual and worldly authority, and his insistence that the two kingdoms be clearly distinguished from one another, tend to prevent the Church from uttering any word at all concerning the life of the world Must it not be accepted that as a result of this demarcation secular life has to be allowed to go its own way The question of the secularisation of society thus comes up with renewed urgency. Are they right who hold that at this point Lutheranism should rid itself of the unfortunate heritage which crippled its activity in the past, and hence surrender Luther's doctrine of the two kingdoms
Luther's Conception of Spiritual and Worldly Authority If we are to come to a correct understanding of Luther's thought regarding the two kingdoms, spiritual and temporal, the kingdom of God and the kingdom of the world, the best place to begin is with his treatise on worldly authority, Von Weltlicher Obrigkeit (1523).
 Luther's writings are, as we have said, directed against this attitude. God is in command in every sphere of life. It is with Him that we have to do in both the heavenly and the earthly kingdoms, in both spiritual and temporal rule. He meets us in both, though in different ways - in the spiritual with the Gospel, in the temporal with the Law. But His will is made manifest to us in both Law and Gospel. The two kingdoms exist side by side, both instituted directly by God for two different reasons. His purpose in the spiritual realm is to make men Christian and to hallow them in Christ, and the instrument He uses to this end is only and always the Word, and the preaching thereof, and the sacraments. In the temporal realm His purpose is to sustain justice and peace in the world, and His characteristic instrument here is power, the use of the sword. In both realms He uses men as His agents. \"Servants of the Lord\" is a name applying not only to those who fill religious offices: rulers are also \"servants of the Lord.\"
 Luther insists that it is of primary importance not to confuse the two kingdoms. Each must be true to its Divine mission. Through the Gospel God rules His spiritual kingdom, forgives sins, justifies and sanctifies. But He does not thereby supersede or abolish the earthly kingdom: in its domain it is to rule with power and the sword. Any attempt to rule the world with the Gospel is a double error, carrying a double penalty. Firstly, the Gospel is destroyed, and becomes a new Law to take the place of the old - man makes Christ another Moses, as Luther puts it. And in addition the world suffers: to quote Luther, \"What would be the result of an attempt to rule the world by the Gospel and the abolition of earthly law and force It would be loosing savage beasts from their chains. The wicked, under cover of the Christian name would make unjust use of their Gospel freedom.\" And again. \"To try to rule a country, or the world, by the Gospel would be like putting wolves, lions, eagles ,and sheep all together in the fold and saying to them, 'Now graze, and live a godly and peaceful life together. The door is open, and there is pasture enough, and no watchdog you need fear.' The sheep would keep the peace, sure enough, but they would not live long.\"
 Luther, in issuing this solemn warning against confusing the two kingdoms or authorities, is setting his face against two different adversaries. On the one side, he opposes the Roman Catholic hierarchy, which in the name of the Gospel lays claim to worldly power, and thereby imperils the Gospel. But he is equally opposed to those whom he calls fanatics. They held that it is the Christian's task to seek to rule society by the principles of the Sermon on the Mount, and that evil should not be resisted, but all earthly law and power abolished. This view is, of course, found in various forms in our day, as it was then. We frequently encounter the statement that the great failure of our society has been that it has not the courage to apply the ethical principles of the Sermon on the Mount to our common life and our relations in the State. Such a view finds no support in Luther. He is against it: it is contrary to the will of God to try to rule the world through the Gospel. God has ordained an entirely different authority to rule the world. It is in accordance with His will that power and the sword are used to that end, and the world is under the sway of that authority, and not of the Gospel.
 Unfortunately, theology has in the past occasionally allowed itself to be led astray by the political trends of the day, and to misinterpret Luther's doctrine of the two kingdoms as a plea for secularisation. It is easy to understand that for those who think solely along political lines it is inconceivable that political life should have to be subservient to an outside will, the will of God. But to hold up Luther on that account as an advocate of a secularised, autonomous political sphere of activity is a grotesque falsification. No-one fought as he did against the secularisation of society. No-one so vigorously affirmed that earthly government is as much God's own rule as is spiritual, and that God never drops the reins from His own hands. How then can anyone throw upon him responsibility for a position which holds State and political life to be sovereign and autonomous A glance into his treatise on worldly authority will suffice to convince one of the utter falsity of the assertion that he preached the detachment of Christianity from State and political life. In almost the first line of his introduction to this pamphlet he says that he is going to \"write about worldly authority and its sword, and how to use the same in a Christian manner.\" Luther realised very well that there is a Christian and an unchristian way of using power. It is not the business of the spiritual ministry to bear the sword, but it must demonstrate the Christian way of bearing it. Without this very often neglected aspect of Luther's teaching, his whole doctrine of the two kingdoms becomes distorted and unintelligible. The Church is betraying an essential part of its mission if it does not continually, by exhortation and warning, remind those in earthly authority of the Law of God to which they are subject. It has not merely to protest when the temporal authorities interfere with its own freedom to preach and to live as a church; it is commissioned to interpret the will of God in regard to the various ordinances He has instituted in the world to regulate man's relation with his neighbours, and to stand forth uncompromisingly against injustice and tyranny. \"To rebuke the authorities,\" writes Luther, \"is certainly not a revolutionary act when it is done at the Divine command and in accordance with the Law of God, openly, fearlessly and honestly. It would, in fact, be much more dangerous to the public weal if a preacher were not to rebuke authority for its injustices.\" 153554b96e