Sometimes you think you’ve lived before 
All that you live today 
Things you do come back to you
As though they knew the way
Oh, the tricks your mind can play!

Lorenz Hart was writing about déjà vu, the feeling that one has previously lived through the present situation, but the mind can play other kinds of tricks. For example— 

That’s a picture of the little room that extends off my den. It’s sort of become a junk room, where I drop things when I don’t know where else to put them.

Notice that Trader Joe’s bag there.

For some reason, and you can’t really see it in the picture, but when I’m walking out of my den and I notice that bag just in my peripheral vision for a second, that bag looks like a teddy bear. The two carry handles sorta look like ears and— Well, as I said, you can’t really see it in that picture. It’s only from my peripheral vision as I walk past it.

But I don’t know how many times I’ve stopped and walked back to check because I could have sworn I saw a teddy bear in there.

Oh, the tricks your mind can play!