How do you know what's inside?

How do you know what's inside?/
There's no way to know.
Even if you think you know, you won't believe it.
If you know, you'll become a god.
If you go back, you'll regret it. You should have left.
I don't know, I don't know, how can I know what's inside?
I know but I don't know,
I don't know, but I feel like I somehow know what's inside.
But in the end, I don't know.
So what are you going to do?
What should I do?
I just do what I have to do.
I am not a god but a human being.
I can understand mistakes and mistakes, but
I need to understand them.
That's the joy of life, that's life. ..