Space - no not the Star Trek variety as in "Space - the Final Frontier, but the gaps in conversation that you need to leave when speaking to someone.
Let me start with this: The only way we can express the worth of our own opinions is by valuing the opinions of others.
Too many times I see sales people (and indeed many others) sitting on the edge of their seats just waiting for a break in the conversation, or waiting until the other person pauses for breath, to jump in with whatever is one their mind.
This is not active listening, and if you are one of these early jumpers, it only demonstrates that you are not really interested in what the other person has to say, and that you think that you know better. You don't have time to consider what the other person has said, nor do you have time to consider your response in the context of what they just said. It is both disrespectful and ineffective.
I remember many years ago when my daughter, then 5 years old, came home from school and told me she was going to be a shepherd in the school Christmas play. Usually she would be excited about going on stage, but this time I sensed only a moderate excitement. When I asked how she was selected to be a shepherd, she responded "Well, the teacher asked who wanted to be shepherds, and me and Alice put our hands up, but, but, but, how were we supposed to know she was then going to ask who wanted to be angels?"
When someone stops talking, it does not mean they have told you everything they are thinking, or that they have said all they want to say. When you make a statement or express an opinion but don't leave adequate space in the conversation for others to consider what you said, or respond fully with their own thoughts, you are missing out on an opportunity to learn, and signalling to them that you are not interested in their opinion.
Leaving space in a conversation for follow on comments or questions, may illuminate areas that you did not even know were in the shade.
The old adage of "You have two ears and one mouth - so you should use them in that proportion", is truly valuable. But if you have one ear on the left side of your head, and one on the right, then you might consider that Space is in fact, as our Star Trek friends would have you believe - the Final Front Ear. (Sorry!)