I found one in the youngwizards books. It is that 'Wizardry does not live in an unwilling heart.' And it is technically true that wizardry does not. But from Deep Wizardry, there is the talk about how most people find that it's normal to have a nameless sorrow at the bottom of the soul. And a blighted wizardry is one of the most dangerous things out there.
It hit me because in the Making Light blog archive that mocks the people who poured gasoline into fluorescent light tubes, someone said that if magic were real, there would inevitably be non-maskable magic-related injuries with people doing Stupid Shit with Magic.
But there are. And it is maskable if you do not know what wizardry does, that instead of gross physical collateral damage, there is mental and emotional damage, and the odd bit of "No one will believe this, so I will not say."
And then there are the people who should have been wizards but who are not. They should have been, but all the energy that should have been devoted to making things better by means of those little daily wizardries instead goes to anger and self-defeating mental poison. It hurts to breathe the same air as them, because they are still broadcasting on wizard channels.
When we say to them, "But you are a wizard," the Lone Power does not even have to step in again, because the Lone Power has already done enough.