Flashback

I'm reading a book "The Design of Everyday Things" by Don Norman. He wrote following:

“To be effective, affordances and anti-affordances have to be discoverable—perceivable. This poses a difficulty with glass. The reason we like glass is its relative invisibility, but this aspect, so useful in the normal window, also hides its anti-affordance property of blocking passage. As a result, birds often try to fly through windows. And every year, numerous people injure themselves when they walk (or run) through closed glass doors or large picture windows.”

This reminds me the situation when my grand mother walked into glass door in the supermarket, when she learned than my mother has cancer.

What a sick flashback...