Re: Quoting O'Sensei
It's also worth remembering that unless you speak Japanese, you are dealing with a translation between two very dissimilar languages and cultures. My dojo has been comparing two English translations of Tohei sensei's "Ki Sayings" lately and they differ quite a lot.
I am not fond of the practice of quoting 1-2 lines from someone's life's work and saying "This is the conclusion X reaches about Y." Generally it's just a debating tactic; there's no room for nuance or shades of meaning, for context, for development over time, or for someone to just plain change his mind. And if you have enough text to pick over, you can come up with support for almost any view you please, as Bible interpreters frequently demonstrate.