In Chapter 20, Prendick uses a metaphor to describe the way the power dynamics on the island settle out after Moreau's death:
Had I kept my courage up to the level of the dawn, had I not allowed it to ebb away in solitary thought, I might have grasped the vacant sceptre of Moreau, and ruled over the Beast People. As it was, I lost the opportunity, and sank to the position of a mere leader among my fellows.
A "sceptre," or "scepter" as it is spelled in American English, is a staff or rod a ruler wields to signify their authority. It is more of a ceremonious symbol than an actual tool. Associated in the Bible with the idea that a ruler is a shepherd for their subjects, the scepter often signals religious as well as political authority. There is no literal "sceptre" Prendick neglects to grasp, but this metaphorical scepter, which symbolizes a divinely-ordained king, represents a role Prendick fails to take on.
Instead of becoming a king or god ruling over his subjects, like Moreau did with his Law, Prendick becomes something more like the leader of a democratic republic. This position is a scary position to occupy because it is precarious. At any point, the Beast Folk might turn against Prendick, and there is no Law stating that they are not allowed to oust him. But in truth, Moreau turned out not to be immune to this kind of uprising even as a religious authority and king. More than anything, Prendick's failure to grasp the scepter represents his disillusionment with the idea that he is any different from the Beast Folk. It is horrifying to him to think of himself as one of them, but it allows him to drop the false pretense of his superiority.
