How Can I Be Sure?

The other day a friend of mine said,
he said the sun's not really yellow,
he said the sun is really red
I said, my friend what do you know,
You read that in some magazine,
Next thing you'll say the earth's not green
How can I be sure of you, when you know,
The world's always changing, rearranging,
Always changing, changing
I said my friend what how do you do,
And what you're saying is not true,
The next thing you'll say the earth is blue
He said my friend you're in a dream,
And things are never what they seem,
Oh things are never what they seem
How can I be sure anymore,
When the world's always changing, rearranging,
Changing...