But at least we shall have added nothing, unless our silence also produces an effect, according to the interpretation he may feel like giving to it, or according to what he may guess from our gestures and expression, or tone of voice. It is so difficult to remove judg(e)ment from its natural basis.
It means that if you say nothing you will not add anything verbally and that's a good thing. But... You may betray or convey what you wanted to say by gesturing in a certain way, and your body language can actually help your collocutor elucidate what is on your mind.
Student or Learner