Do we know?

Oh, but now old friends they're acting strange
And they shake their heads, they say I've changed
Well something's lost, but something's gained
In living every day

I've looked at life from both sides now
From win and lose and still somehow
It's life's illusions I recall
I really don't know life at all

It's life's illusions that I recall
I really don't know life
I really don't know life at all

- Joni Mitchell