The present

Everyone has left the Lighthouse but the Teacher. He stands staring at the blackboard, trying to make sense of the tangle of equations. Then he makes a startling discovery...

[Teacher]
Will we ever understand
How two different hand styles
Came to grace this blackboard?

What unseen forces did conspire
Uniting a father, and his son...

[Whisper Outro]
The integral from zero to infinity... help me!