In this Volume, the topics are all of concrete and vivid interest.

Several of them trace principles still in process of growth.

Research has in some important respects revealed different results to different scholars working on the same materials.

Hence occasionally the added interest, for the student, of reconciling the conflicting beliefs, or of choosing between them.

For those who must decline either alternative, there remains the consolation proffered six centuries ago by the seer of Italy, " To doubt is not less grateful than to know.