The entire collection of novels that established Galsworthy as a writer of considerable fame are an example of social criticism which expose the upper-middle class of England as suffering some sort of decline, both moral and spiritual, as represented by the Forsyte family. Let us remember that they are so avaricious and so blind to anything else outside of their own frame of reference that they are unaware of how society is changing and how it will fast outpace them, leaving them stranded and defenceless in the new world of the 20th century with all of the changes that it brings.
This is something that is achieved through Galsworthy's descriptions of the kind of backdrops that make up the life of the Forsyte family. He variously describes business meetings, receptions in claustraphobic drawing rooms and weddings that are characterised by a lack of happiness. These are shown to be the ingredients of the upper-middle class that is losing its spiritual and moral roots. Note how the following quote, describing Soames Forsyte, uses irony to mock his sense of self-assurance and his immense self-belief:
His natural taciturnity was in his favour; nothing could be more calculated to give people, especially people with property (Soames had no other clients), the impression that he was a safe man. And he was safe... How could he fall, when his soul abhorred circumstances which render a fall possible--a man cannot fall off the floor!
For Soames, a man obsessed with his property and its acquisition, there is nothing else apart from appearing to be a "safe man." Yet the text makes clear that his very greed is something that blinds him to what is going on around him, making him into the equivalent of a dinosaur who is unable to adapt to the changes in his environment.