How Do You Know?

People sometimes ask,
If you believe in love at first sight.
Some say it's just a coincidence,
Like being born black or white.

But how do you know,
That the sun will always rise?
Then have its place taken by the moon,
Which fills every star-lit sky.

How do you know,
That no matter how long it rains.
It will eventually have to stop,
Leaving only a blue sky to remain.

How do you know that your grandfather,
Who's eighty-three and a half,
Will tell the same joke over and over,
And that each time you'll still laugh.

How do you know,
That your parents will always seem to cry,
After you've hugged and kissed them,
Knowing it might be a final good-bye.

How do you know that death comes,
And that each of us eventually has to go?
The same way I know you can love,
From just a simple and friendly 'hello'.