Benjamin took the sack and knelt down. He took a small phial of oil from his pocket, poured it over the sack and struck a tinder: the rough, dry cloth was soon alight. Benjamin climbed out of the hole and we both watched as the flames roared, turning the sack to blackened ash. I must say I was fascinated. Only the good Lord knows what was in those cures. I mean, it's not often you see blue fire! Benjamin took me by the shoulder. 'It's the best way, Roger. It will keep you out of villainy. I don't want you going into London. I don't want you seeing Miranda. And I don't want you selling medicines. Do you understand?'

I blinked innocently. Benjamin smiled, shaking his head and, taking his spade, began to fill the hole. I stood and watched, fingering that old spearhead in my wallet; already a vague idea was beginning to form but silence is the best counsel to follow in such matters.

We returned to the manor. Benjamin now seemed light-hearted, and the tension between us had dissipated. I decided to relax and enjoy the golden autumn sun. The next day I was supposed to be helping with the early harvest I forget the precise details. Anyway, whilst everyone else was working, I and young Lucy Witherspoon found ourselves on top of a haystack. I was teaching her the principles of mathematics and counting, using the laces across her ample bodice as an exemplar. I had just reached the last lace when I heard Benjamin call my name. I looked over the haystack, whispering at Lucy to stay there with the wine I had brought Benjamin was staring up at me.

'Roger, come down. You look tired. You've been too long under the sun!'

I just ignored him, my flesh already turning cold at the sight of the visitor standing next to him: Doctor Agrippa! I have talked about this creature many a time. Of medium height and cherubic face, Agrippa had twinkling eyes which could, at a drop of a coin, turn iron hard. As usual he was dressed in sepulchral black from head to toe, his jovial face almost hidden by the broad-brimmed hat.