Not to listen is to be like a pot turned upside down. Not to be able to retain what you hear is to be like a pot with a hole in it. To mix negative emotions with what you hear is to be like a pot with poison in it. 

The pot turned upside down: When you are listening to the teachings, listen to what is being said and do not let yourself be distracted by anything else. Otherwise, you will be like a pot turned upside down, on which liquid is being poured. Although you are physically present, you do not hear a word of the teaching. 

The pot with a hole in it: If you just listen without remembering anything that you hear or understand, you will be like a pot with a leak. However much liquid is poured into it, nothing can stay. No matter how many teachings you hear, you can never assimilate them or put them into practice. 

The pot containing poison: If you listen to the teachings with the wrong attitude, such as the desire to become great or famous, or a mind full of the five poisons, the Dharma will not only fail to help your mind; it will also be changed into something that is not Dharma at all, like nectar poured into a pot containing poison.

-- Patrul Rinpoche