Knowledge Gaps

I was stunned yesterday by a woman in the bookstore who was perhaps ten years older than me and who, as I overheard, was not ashamed to admit that she didn't know during which years the Second World War had been fought.

However I do not know if my Christmas tree is a spruce or a pine (though I am pretty sure it's not a maple) and I don't know if my own ignorance is any less troubling.