After making your size-up of the degree of his mental speed, you can govern your presentation by what you have learned.
Therefore it is not safe to rely on a size-up based on what he says.
This is the reason why your size-up should be restricted to discriminative observation of indications of the ego.
It is better to make no size-up at all than to strain in observing the other man and make him aware of your close scrutiny.
Therefore restrict your size-up to the discriminative observation of the muscle signs of his mind habits and mind actions.
Therefore teach yourself to observe without seeming to look closely at the object of your size-up.