Power. Professor Black had social power, academic power, and professional power; yes, Clue could see why any student of Hogwarts would consider their Headmaster to be the most powerful soul they knew. "I agree with you", he thereby said.

Clue mused silently as he took another bite of the pastry. It had meat in it. And that reminded him of someone; a butcher, an evil butcher, powerful, very powerful.

"But I'd also argue that a person with great sway over one, has more power than a person with sway over many."

Phineas Black could bend a meadow of flowers to his will. But if there was only one flower in that meadow, he could stamp it ten feet into the dirt.