Briefly, this is his history.

He was originally a witch-finder--about as low an occupation as exists amongst aboriginal savages.

Then he got up in the world and became an Obi-man, which gives an opportunity to wealth _via_ blackmail.

Finally, he reached the highest honour in hellish service.

He became a user of Voodoo, which seems to be a service of the utmost baseness and cruelty.