When a very young child sees a line intersecting a circle, the child 
knows if the line is perpendicular.  Even if the curves were quite 
complex, the child would know.  

When the child grows up, he might take a class in linear algebra and be
able to explain it.

Explaining it to a child, the child would be very bored.

Explaining with a bunch of words to one who just knows intrinisicly, would
be very boring.  I think maybe even worthless.

We do it all the time, and it's very boring, and I think maybe even 
worthless.

I imagine most of my thoughts trying to understand things seem very boring
to one who knows.  At some point, they cease to amuse.