Two ears, one mouth.
Every now and then, we'll find ourselves in the presence of a master and we'll be lucky enough that they be in an open state of mind to share their knowledge--about everything. If we play our cards right in this situation we can either leave a better person, or not. I've been lucky enough to be in many of these situations and I think should you do certain things, you'll have more of these situations come to you.
It's simply this: Listen to understand. Don't listen to reply.
It's important you view these moments as learning opportunities. This is where real learning happens--through genuine conversational exchange. Not through school. So don't waste time trying to contribute, or add to the conversation. They are the master, and you stand more to gain by listening than talking. Don't waste words and create noise either. You just end up obscuring what the master has to offer and in effect, diluting your ability to improve as a result of what was shared.
Ask questions, and ask for elaboration. Ask, then listen. Repeat.