In Chaucer’s day, there were just two recognised classes: the nobility (which included the higher clergy) and the common people (who were simply defined by being not-noble).
You will come across people who refer to the nobility, even at this early period, as the “aristocracy”—but the word ‘aristocrat’ was only coined during the French Revolution, and, while it may be of passing use to define specific attitudes which can be identified among the nobility of Chaucer’s time, it only results in fundamental confusion if it is used as a generic synonym for the actual class.
Examining the facts of life in Chaucer’s time, we can identify a third unofficial class: the class of business people (or ‘merchants’, as they were called.). And, for what it is worth, we can get a sharp idea of the attitudes of this unrecognised class from Chaucer’s Merchant’s Tale. (Literary critics who approach this tale simply as literature often suppose that the Merchant who tells the tale has things in common with the knight (i.e., a nobleman) who is its main character, and miss the Merchant’s class envy. I may have more to say about this in a later contribution to this site.)
‘Trade’ was still despised by the nobility in Jane Austen’s time. But by then a third class had come to be recognised: the gentry. Jane Austen herself wrote about the gentry, and stood up for people in ‘trade.’ But she despised money valuations (see the opening paragraph of Mansfield Park) and had no time for the nobility, whom she regularly mocks.
In the twenty-first century, the ‘nobility’ may be separately recognised as a group among the owning class, but more for their celebrity value (see my ‘Stardom’) than any sense that they constitute a distinct class. The ‘gentry’ are even less likely to be recognised as a group.
Two main classes
I myself find it helps at this point in history to recognise only two main classes: the owning class and the working class. And they are easily defined. You are a member of the working class if you need to work for a living. You are a member of the owning class if you own enough—in the way of land, property, stocks and shares, etc.—never to need to work. (You may actually work, but you don’t need the money.)
The third class is of course the ‘middle class’. It is hard to find another expression which is used so widely without there being any accepted definition. It was a term of abuse used by the last vestiges of the nobility right up to the 1930s. (John Betjeman’s well-born mother-in-law tried to persuade her daughter not to marry the poet on the grounds that he was “so middle class.”) C S Lewis noted in the 1950s that the expression was now mostly used by the working class—but still as a term of abuse .
Actually this third class is not that hard to define. You are a member of the middle class if you own a fair amount of land or property or stocks and shares, etc. (in the wonderfully revealing expression, you have “money of your own”)—but you don’t get enough income from them to avoid having to work.
Is this how most people define the middle class? Hardly. Instead, many (most?) people use this term not for a real economic class, but for what sociologists call a “status group” (defined by its attitudes and behaviour). Or they separate the working class into two groups—e.g., salary earners and wage-earners, or people with mortgages and people who rent—and call the first group “middle class.”
As a result, many people think of themselves as ‘middle-class’ when my criterion doesn’t apply to them at all. They are simply educated members of the working class (like me: in my eighties now, I have never owned anything which brought me in any income, and when the Abbey National building society turned itself into a bank, and sent all its members a handful of shares, I was waiting outside the former building society’s premises in Oxford before it opened, in order to hand them back.)