It was a genuinely surreal experience.
Damien wasn't a person with doubts.
He was assured in himself and he was assured in his power, so something like enlightenment wasn't an experience he had often, if at all.
Every time he'd been "enlightened," it came as a result of his consistent effort, or as a result of a clue given by someone else.
Then what about this time?
While the unrecorded man's words that gave Damien knowledge of the six pieces he needed and the concept of harmony could be considered a clue, it wasn't much at all.
It gave Damien a path forward, but it didn't tell him how to walk it. It told him what could be done, but it didn't tell him how to do it.
And more importantly, it didn't really touch upon the grandiosity of Existence.