One theme of this poem is that appearances can be deceiving. We cannot tell, just by looking at another person, what they are going through or dealing with personally and privately. Someone might appear to be happy or contented with their life —and we might have every reason to believe that they are—but that appearance of satisfaction does not necessarily mean that a person isn't suffering secretly. In the poem, everyone in town "look[s] at" Richard Cory whenever he ventures out. He is, evidently, quite envied for his wealth, his attractiveness, his "grace," and the speaker says that he is "richer than a king." While these "people on the pavement" work nonstop and still do not earn enough money to supply their tables with sufficient meat or bread, their admiration and envy of Richard Cory's wealth and security likely leads them to believe that he is happier than they. The speaker says that Cory "glitter[s]" when he walks and "flutter[s] pulses" when he says even the most mundane of greetings. Judging from language such as this, no one would expect the man to be unhappy, let alone so miserable that he would feel driven to take his own life.

Another important theme is that wealth does not make a person happy. We do not know precisely what Cory is so unhappy as to take his life, but we do know that he must be quite unhappy to do so. We also know that he is incredibly wealthy, and these understandings lead to the idea that being wealthy doesn't necessarily lead to being happy.

"Richard Cory" was written by Edwin Arlington Robinson in 1897 and reflects a period of high income inequality in the United States, exacerbated by the Panic of 1893, a depression caused in part by bank runs. 

The first theme of the poem is economic inequality. Rather than wealth being distributed evenly within the town, it is unequally distributed, causing significant social stratification. Although Cory is apparently polite and not disliked, there is a vast social gulf between him and the townspeople and no possibility of friendship or even shared activities and interests.

The second theme is that money does not bring happiness. Although Richard Cory was "richer than a king", he still committed suicide.

A third theme is the impossibility of knowing what happens within the mind of other people. The nameless narrator of the poem observes Richard Cory from the outside, thinking:

In fine, we thought that he was everything

To make us wish that we were in his place

The narrator, though, has no idea whether Cory is actually happy or not or whether his "place" is pleasant. 

Upon reflection of those who "glitter when they walk,"--the celebrities of contemporary society--one must note that, like Richard Cory, they inhabit rooms of which no one else has knowledge. (One fairly recent example is that of Philip  These rooms, some of which may be the proverbial "brown study" or the blackest despair of the soul, are apparently ones in which those above "the pavement" of ordinary lives wrestle with unconquerable torments, while the ordinary people "who cursed the bread" in their discontent and envy of the rich and famous live out their banal lives.

Edward Arlington Robinson's poem "Richard Cory" relates the truth that all persons are inscrutable to others; for no one can truly know all that dwells within another's mind. Thus, Robinson touches upon the theme of the existential aloneness of each human being. Paradoxically, this aloneness of Cory was exaberated by his celebrity. For, when he comes to town he is alienated from the citizens because of their perception of him as "imperially slim" and "schooled in every grace," and far above them in stature, so much so that no one really communicates with him.

Two themes are developed through the poem's ironic ending. Although Richard Cory enjoyed wealth and social position and was much envied by the working poor, he is the one who commits suicide, as we learn in the poem's last surprising line. The public perception of Cory when contrasted with his suicide develops several themes. All of his wealth and privilege did not bring Cory happiness. Apparently more is required to lead a meaningful life. Also, appearances are deceiving. Those who watched Cory, a man who "glittered" in their eyes, assumed he enjoyed a perfect life. They had no idea that his life was so empty and unbearable.