This week's visiting Head of State, M. Leopold Senghor of Senegal, is one of the most cultivated politicians in Africa - as befits the President of one of its most civilised republics. M. Senghor, 55 this month, is an able scholar, a former brilliant teacher in Paris and a considerable poet. Another distinction, by Senegal standards, is that he is Catholic. The country's population is predominantely Muslim, and Senghor's election seems to testify to the tolerance of both President and electorate...