What is the white stuff?

"Dear Cocoa,

What is the white stuff that flies about...

I don't usually read gossip columns, but my friend told me you could answer my question.  If you can, I will be an avid reader from this moment on.  So here it is:  I have been an inside cat all my life and I spend hours in the windows watching the world go by.  I have often seen white stuff floating tantalizingly close to the window but just beyond my reach.  I have wondered often what this stuff is and why I can see it but not play with it.  Can you help me?

Signed Wonders about the white stuff"

"Dear Wonders about the white stuff,

What you are seeing is dander.  Yes, I said dander.  The large felines of the world have been saving their dander all during the hot days and now they are shaking it off to allow the warm fur to grow and keep them warm.  You could play with it, I suppose, I have seen others do so; however, I would never stoop to such levels.  I mean really, why would I want to play with another feline's dander?  I have enough of my own to deal with.  I hope you will become a very avid reader of my column and I thank you for giving me a chance to answer your difficult question.

Signed Cocoa"