The looking glass. What is it? Is it not that glass that make things appear bigger?
This is my understanding. That when you scrutinise something detail for detail you look at it "Through the looking glass."
But then when you read alice in wonderland it has another meaning. (Most men didn't so I don't think that a man might uses this meaning)
Lets see if I get Lewis' version on the net.
adjective
Definition:
with everything wrong way around: characterized by the complete reversal of everything normal ( dated )
[<Through the Looking-Glass (1871) by Lewis Carroll]
