IT HAPPENED SOMETIMES in the practice of physics that the student, having wrestled for hours with a recalcitrant equation, would suddenly find a way to wreak some drastic simplification upon it. Of a sudden, two terms, which he had copied out time and again, and which had become as familiar to him as his own signature, would, through some insight, or the providence of some new scrap of information, turn out to be equal to each other, and vanish from the equation altogether, leaving a wholly new mathematical sentence to be pondered. The student’s first reaction was exhiliration: pride at his own cleverness, mingled with a sense that at last he was getting somewhere. But soon sobriety took over, as he pondered the remade equation and became aware that he was really just starting on a new problem. Thus Daniel in the Black Dogg, trying to re-think all. For example: Jack Shaftoe was wearing a sword. When he had been Sean Partry, Daniel had scarce noted this, for many men went armed. But for Jack to be armed, here and now, was no mere affectation. He had set it all up so that he could kill Daniel and Isaac, if it came to that. And the king’s ransom in fine bright candles: from Sean Partry this had been simply bizarre, but from Jack it was a way to get a good look at his interlocutors’ faces whilst keeping his own phizz cloaked in the dazzle. And these were just the simple and superficial matters. Daniel would be puzzling over the deep bits for weeks.