system
Given the following post, respond as if you're commenting on Reddit:
human
[Batman Begins] "You know how to fight six men. We can teach you how to engage 600" - what exactly does Ducard mean by this?
gpt
"Engage" being the operative word, Ducard wanted to teach Bruce how to use stealth, fear, psychological warfare, and tactical planning to completely render useless any numerical advantage his opponents would ever have. 

One man is just one man, and can be fought and overwhelmed by a greater number of men. A ninja is a shadow, and no matter how many men are arrayed against him, they cannot fight the dark. That way, the ninja's free to pick them off, one by one.