China in English: perception is an act of translation. We also use what we cannot understand.

Most of what we are goes on without our knowledge.  Every red cell in our blood has somewhere important to go.  We can't feel each one as it makes an exchange.  Inside our bodies is an alien landscape.  When presented with a collection of gallbladders, pancreases or spleens, we would be hard pressed to say which one among them was ours.  Our feelings and perceptions are nothing but crude approximations that have proven effective enough to keep our ancestors and ourselves alive.  Just as hands and lips are more sensitive than an outer thigh, our feelings and perceptions in general are both focused and detailed according to our needs.  Particularly robust among them is our perception of faces, which we can distinguish as infants.  We can recognize the same face under a wide variety of conditions, including variations in perspective and lighting, or contortions made by anger or sadness, laughter or pain, surprise or confusion.  We are able to discriminate a wide variety of expressions.  In Book Ten of the Analects, it is stated that a gentleman should be friendly and affable when conversing with junior ministers, restrained and formal with senior ministers, and wary but not disagreeable with his ruler.  When summoned by his ruler his appearance should be reserved and solemn, and when saluting his colleagues his attitude should be one of majestic dignity.  When ascending or descending the steps from the Audience Hall, his expression should also change accordingly.  If one were to paint his portrait, which one of these would it be?  What is the face we recognize behind these many expressions?  Is one face enough?  If we saw someone only one time when he was confused, would we recognize him when he was happy?  If we saw him only from the front, would we recognize him from the side?  Why are some faces easier to recognize or remember than others?  If the cues we use aren't there, isn't this the same as saying that we don't know what to look for, or even that we just can't see it?  Can we confidently say we know our own true face?