"Seers can be wrong," Zacharias informed him tartly. "In fact, Divination, in general, is a whole lot of rubbish." There were only a handful of real Seers out there after all. And who said Merlin was one of them? "Just because you claim to have the Sight doesn't mean you do. You could be making all this up." For all he knew at least.
Although he had to admit, he liked the vigour that sprung into Merlin when he accused him of being wrong. Why, he snapped at him! So he had some backbone after all.
"Well what did you see then, hmmm? If it's about me, I have a right to know."