Why

Why is it that my cat (her name is Lizzie Andrew Borden, she is Siamese) relentlessly tries to convince me that she cannot sleep unless she is on my lap - or at least touching me?  I wonder if she actually believes that I do not know that when I am not at home she sleeps in my chair. On the sunshine window sill. Under my bed. On Mom's bed. In my closet when I miss the hamper and a top has missed the basket and fallen on the floor. In the linen closet when I don't latch it and she pries it open with her nimble fingers. And other mysterious places I have not discovered as yet.

I wonder why she doesn't use her heated bed I bought especially for her.