a perfect foil [book quote]
"Holmes was a man of habits... and I had become one of them... a comrade... upon whose nerve he could place some reliance... a whetstone for his mind. I stimulated him... If I irritated him by a certain methodical slowness in my mentality, that irritation served only to make his own flame-like intuitions and impressions flash up the more vividly and swiftly. Such was my humble role in our alliance."
- from The Adventure of the Creeping Man