Conrad Dieterich was, during the first half of the seventeenth century, a Lutheran ecclesiastic of the highest authority.
His ability as a theologian had made him Archdeacon of Marburg, Professor of Philosophy and Director of Studies at the University of Giessen, and "Superintendent," or Lutheran bishop, in southwestern Germany.

In the year 1620, on the second Sunday in Advent, in the great Cathedral of Ulm, he developed the orthodox doctrine of comets in a sermon, taking up the questions: 1.

What are comets?
2.

What do they indicate?
3.

What have we to do with their significance?
This sermon marks an epoch.