Ajahn Chah would often give the following example: we can take a glass and call it kaew nam in Thai; in the Pāli language we would refer to it differently; in Chinese, in Hindi, in English it is called something different still. Because actually there is no glass. It’s just elements that humans have brought together in a certain way to produce this thing. If the elements are pulled apart again then it isn’t there. It’s empty. This is what is meant by convention.
[He] gave the example of a duck and a chicken. Presently we say that a duck goes, “quack, quack” and a chicken goes, “cluck, cluck.” But if it happened that they had called ducks “chickens” and chickens “ducks,” then presently we would call that which goes “quack, quack” a “chicken” and we’d be calling our chickens “ducks.” Our mutual understanding is just based on conventions.
…In actuality, it’s not correct. These are simply labels which we have come to use when referring to things. But the mind takes these conventions to be real and clings to them as such— that there are animals and people and selves. Attachment is born, which is the cause for the arising of suffering. We need to really investigate this! When you allow the heart to see the truth it can then arrive at emptiness.
But we firmly cling to these things as if they are real. If somebody calls a glass a chamber pot it disturbs us. “Please hand me that chamber pot,” someone says and we feel like, That’s not a chamber pot, it’s a glass! But these are only conventions. If we really contemplate these things, the heart will be released. We will realize that until now we had never fully understood the truth. In reality, there isn’t any thing there. When we understand the truth, the heart becomes bright and clear. It’s as if the heart, fooled by conventions for so long, has been turned upright. It has been liberated from attachment, realizing that all the things of this world, including this body and mind, are without any abiding essence of self. It’s just not correct to take them as a self. According to conventions one may say there is a self, but one knows it’s not a true self. When it’s like this one has seen the Buddha.
These reflections by Ajahn Anan are from the book, The World and the Heart, pp. 62-66.