Warning: contains spoilers for A Discovery of Witches season 2 episode 8.
Near the end of A Discovery of Witches season two, episode eight, Peter Knox walks into the hospital room where new parents Sophie and Nathaniel are recovering from the birth of their daughter Margaret (no, nobody else is much keen on the name either). As a powerful witch who represents his people on political assembly the Congregation, he’s there to verify that the baby is – as he’s been told – a witch born to daemons, and then to kidnap the child so that she can be raised by her own species.
Knox holds up a small carved ball, which instantly stops Nathaniel in his tracks and drags him over the floor where he collapses at Knox’s feet. The witch then flourishes the ball at Sophie, and as he utters the command ‘sleep’, it emits a wave of energy that also knocks her unconscious.
We’ve seen Knox work magic of this kind before. He used these balls to torture and control Satu in season one, and instinctively reached for them as a weapon when vampire Gerbert entered the Witches’ Archive in last season’s finale.
The objects are clearly intrinsic to Knox’s spellcasting as a conduit for his magic and a way of focusing it onto a specific victim. When he used one to control Satu, it functioned much in the way of a voodoo doll – when the ball was twisted, the victim twisted. Emitting a kind of electrical sound indicative of the magical energy channelled through them, the balls are clearly powerful and even deadly. Knox holds one over Satu’s head while his magic is pinning her to the table, and threatens to crush her using the weight of magical gravity.
Unlike Diana and Satu, Knox is not a weaver (a witch capable of inventing spells by tying together the threads of life), nor does he seem to have elemental or instinctual powers in the same way that Diana does. His magic is all about spellcasting and incantation, which is why he relies on the spheres. As the actor who plays him, Owen Teale, explains it in this Sky interview:
“Peter Knox is one of the finest to invoke the power of chant and spell, through ancient ritual. He’s a master in getting into other people’s minds. He has the power of possessing another person’s thoughts, whereas Satu really can move heaven and earth.”
To give Knox’s magic balls a less vulgar name, we should properly call them ‘petrospheres’, the name given to real-world mysterious carved stone spheres discovered across Scotland and other areas of what is now the United Kingdom, dating all the way back to the Neolithic era. Though the character is played by Welsh actor Teale, ‘Knox’ is a Scottish surname, which makes his choice of magical object geographically appropriate to him. (Creator of the All Souls trilogy Deborah Harkness is a scholar who finds countless ingenious ways to weave real-world history into her fantasy series.)
The function of real-world petrospheres is debated, with suggestions that they were used as projectiles or primitive weights, oracles to interpret messages from the gods, or ‘right to speak’ objects that temporarily imbue the person holding them with power. That last one would no doubt appeal to a character like Knox, who is driven by his obsession with the supremacy of the witch species.
Knox believes that witches created their enemy – vampires – using a spell detailed in the Book of Life. He desperately wants to find the book so that he can un-create the vampire species, before, as he sees it, they do the same to witches. When Diana refuses to help him in season one because she finds the idea of species genocide abhorrent, Knox tells her “They would do exactly the same to us.”
His character, according to Teale, is an object lesson in the wrong way to exist in the modern world:
“Through Peter Knox, we’re able to reveal obsession in a goal is going to make you intolerant, that we fear the unknown, that we blame, judge, instead of trying to accept and understand.”
So those are Knox’s petrospheres, magical objects through which his spells are channelled that mark him out as a very different witch from the instinctively powerful Diana Bishop, and a very different person.