Read my latest comments. If you need further clarity, ask me specific questions and I will attempt to accommodate them.

But to give some additional note on the quote you provide, look to reductio ad absurdum as a case where it would be incorrect to aver to the truth of what is really contradictory in nature. If it still isn't clear, ask yourself this: "does it make sense to say something is true when it is actually false?" Anyone who answers this in the affirmative is either being silly or needs to have their head checked (for some fascinating stuff, indeed).