The novel critiques the Victorian faith in progress. Wells is saying that we can't just rely on the passage of time to make society better and more just. The Time Traveller goes roughly 800,000 years into the future. All the same, the gap between the social classes has not been closed—in fact, it is worse than ever, and the Elois live in constant fear of the Morlocks. The Elois are also (perhaps like Victorian society in the 1890s) a society in decline. Through his novel, Wells argues that we need to deal with our social problems or they will simply get worse. We can't just sweep them under the carpet. Things change all the time—they are certainly different in the future—but they are not necessarily better.

The novel also critiques the Victorian leisure class through depicting the decadence of the Elois. They do nothing for their money, while living on the proceeds of other people's labor, a lifestyle which Wells frowns upon. Further, while the Victorian upper classes in England were proud of not having to work for a living, Wells argues that this actually damaged them as well as the lower classes, who were overworked in order to support them. Is it it worth it to keep the Morlocks in a world of darkness so that the Elois can live in a pastoral world of beauty and light in which they don't achieve anything?

Interestingly, the novel explores the meaning of time. As previously stated, the Time Traveller journeys 800,000 years into the future, so far away that even the nature of the physical world is changing because of changes in the sun. Wells raises the question of whether it is even possible to understand the past or the future because we bring with us too many assumptions from our own time. In this sense, Wells echoes Nietzsche in seeing humans as caught in a "prison house" of language (and society) from which we can't wholly escape. 

One important theme is that of class conflict. Wells himself lived at a time when industrialization was contributing to enormous class inequalities, and the time traveller discovers that a form of class division has persisted into the future in the form of the Eloi and the Morlocks. The traveller posits that the Morlocks evolved from the working class, and the Eloi the capitalists.

Another theme is that of technology. The turn of the century was a period when technological inventions were changing people's lives, especially in the cities. There was a tremendous faith in progress among elites. The Time Machine suggests that this faith may be somewhat misplaced. As he travels to 802,701 AD, he discovers that human beings have been replaced by other species of beings. Thirty million years in the future, there are no creatures at all except for a hideous blob with tentacles.

Finally, there is the theme of evolution, implied by the previous theme. Human beings have evolved into the Morlocks and the Eloi, as a result of their ability to adapt to their different surroundings. Each of these themes suggests a warning against overly-optimistic views of progress, underscored at the end of the book in a description of the traveller:

He, I know—for the question had been discussed among us long before the Time Machine was made—thought but cheerlessly of the Advancement of Mankind, and saw in the growing pile of civilization only a foolish heaping that must inevitably fall back upon and destroy its makers in the end.

The narrator feels differently, but the overwhelming message of the book can be construed as a warning against hubris and faith in progress.