A pot turned upside down cannot be filled. When we are distracted, unwilling to learn, or preoccupied with other matters, it is not possible to receive the teachings. This mental state is compared to a pot turned upside down, because no matter what substance may be poured into it, there is no opportunity for it to enter the vessel. Whenever we approach a teaching, we should be fully attentive, willing to learn, and undistracted.
A pot with a hole cannot retain. If we listen attentively to the teaching, but immediately turn our minds to other things, we will not retain anything of what we have learned. This is compared to a pot with a hole, because whatever substance may be poured into it, it will not long remain. Whenever we listen to a teaching, we should reflect on the meaning of what we have heard, and begin to apply it in our daily lives.
A pot with poison cannot remain pure. If we listen to a teaching while our minds are afflicted by attachment or aversion, instead of retaining what we have learned as it has been taught, we will mix the teaching with our afflicted emotions. This is compared to a pot already filled with poison, because whatever substance may be poured into it will become contaminated with the existing toxic content.