In context, this is said right before the battle of Agincourt and Henry V is reminding his troops that the only thing left for them to do is to prepare their minds for the coming battle (where they are horribly outnumbered). I guess the rationality part is to remember that sometimes we must make sure to be in the right mindset to succeed.

I've always seen that whole speech as a pretty good example of reasoning from the wrong premises: Henry V makes the argument that God will decide the outcome of the battle and so if given the opportunity to have more Engli... (read more)