the Veil

The Veil is the precept of magical society stating initiates must actively guarantee that non-mages are kept ignorant of magic and the supernatural. It was established at the Cairo Concordat as a way to avoid that non-practitioners turn against mages and persecute them as they once did in the century that eventually led to the Gray Age. This precept is thoroughly enforced by the Council through the Protectorate, but practitioners ordinated in the Arcanum must pledge to uphold it.
It is believed that, given contemporary magical society, events similar to the ones that led to the Gray Age are highly unlikely to happen again, but it is still agreed that revealing the arcane to non-mages would doubtlessly cause mass panic. While more confident practitioners believe that mages would most likely triumph in open conflict, most still shun the idea of a war, because the price would be the death of fellow humans, even if non-practitioners. There is also the argument that modern warfare technology could simply lead to mutually assured destruction.