Help me with the Quote please

[lefulefulefu]

I'm struggling to remember one of Sheldon's quotes. I have very limited information about it. Plese help me.

Information i know : there is a same verb used twice in that quote and there is ''because'' or "therefor" between those verbs, 

like for example:  i am because i am, i exist therefor i exist .  It might be or most probably is part of a longer quote, monologue of Sheldon 

in which "i exist therefore i exist'' like expression is at the end of it. Thanks for your help because i can't figure it out for couple of days.

English is not my first language so i'm sorry for mistakes or if something doesn't make sense :D

Edited October 29, 2017 by lefulefulefu

[bfm]

Could it be from his talk with Penny in "The Spaghetti Catalyst"? If so you can google the transcript for that episode.

[Tripper]

As bfm says, maybe it could this from The Spaghetti Catalyst: 

Quote

Penny: So, how you been?

Sheldon: Well, my existence is a continuum, so I’ve been what I am at each point in the implied time period.

Or this from The Gorilla Experiment:

Quote

Sheldon: Why are you crying? 
Penny: Because I'm stupid. 
Sheldon: That's no reason to cry. One cries because one is sad. For example, I cry because others are stupid, and that makes me sad.

Or perhaps this from The Gothowitz Deviation:

Quote

Penny: You know what, I give up. He’s impossible.

Sheldon: I can’t be impossible. I exist. I believe what you meant to say is, “I give up, he’s improbable.”

Or maybe this from The Skank Reflex Hypothesis:

Quote

Sheldon: If I could I would, but I can't so I shan't.