It wasn't long before his knowledge showed through

[keannu]

What does "showed through" mean here? Even before introducing himself, how could he show his knowledge?

gu130)All of Dr.Lloyd Pinkham's students owe him a debt of gratitude...I remember the first time we met him. He was sitting in the classroom, wearing shorts and a t-shirt and sipping a soda. No one realized who he was, so we started chatting casually. It wasn't long before his knowledge showed through, and at that point he stood up, introduced himself, and delivered the best lecture I've ever heard. I can barely hold bak my tears at the thought of never seeing or talking with him again.

[Rover_KE]

When he was chatting, it became apparent that he was a knowledgable man.

Rover

[keannu]

There is no indication that he started chatting before he stood up, though.

[bhaisahab]

There is no indication that he started chatting before he stood up, though.

"No one realized who he was, so we started chatting casually."

[keannu]

Isn't "we" me and my friend excluding him?

[Rover_KE]

He was clearly included in the chat for his knowledge to show through.

Rover