Is this a real quote from Kant?
“Someone’s intelligence can be measured by the quantity of uncertainties that he can bear”
If so, what is the origin? In what context does he say it?
I don't know all of Kant's work but I know mainly his point was that using your reason is what gives you freedom, makes you human and is what gives hope to humanity. He never talks about knowledge, he talks about using your own intelligence. In other words, questioning things. He says weak people go for the easy answer, all made for them, all prepared. The hard thing to do is not be sure, is questioning and finding your own answers. Therefore, the more intelligent (and strong) you are, the more you're able to see things as uncertain and don't need the stable certitude of some pre-digested knowledge.
His text called What is enlightenment? is mostly what can be interpreted such as "Someone’s intelligence can be measured by the quantity of uncertainties that he can bear". But I have to say, even though its meaning made sens with my knowledge of Kant's theory, I never saw this quote within his work. I spent the afternoon trying to find it and, just like so many people, I can't. I really don't want to give up because it seems like something Kant would say, but so far, it only seem to be an interpretation of a part of his work.
Refer to Kant's What is Enlightenment? text.