“- Philo Vance: What do you think of the suicide theory now, Sergeant?
- Detective Heath: Well, it's slightly complicated since the man shot, slugged and stabbed himself - especially in the back.”
William Powell - Philo Vance
Eugene Pallette - Detective Heath

“- Mr. Taggart: We've no guarantee that these theories of yours are workable.
- Thomas A. Edison: Well, most electricity is theory yet.”
Gene Lockhart - Mr. Taggart
Spencer Tracy - Thomas A. Edison

“He had a theory that if you should find one perfect thing, or place or person, you should stick to it.”

Joan Fontaine - Mrs. de Winter

“As much as I enjoyed your wild theories the truth is far less complex.”

Timothy Dalton - Simon Skinner

Although he was considered insane by his peers, Bernoulli's theory states that the air flowing over a bird's wing is at a lower pressure than the air flowing under the wing. That's called "lift". Of course, it's only a theory, it's never been tested...

Kevin Kline - Artemus Gordon