What a thesis statement of the book The Time Machine?
A strong thesis must state an opinion. In other words, it must be arguable. A thesis statement, for example, shouldn't only say that the novel is about traveling 800,000 years in the future, because that is a "fact" revealed in the book.
Beyond stating an opinion, the thesis should be specific. For example, you wouldn't want to simply say that the novel was about class struggle. You would want to state what about class struggle Wells was exploring or critiquing. For instance, a strong thesis might argue that Wells was not worried about small differences between classes but arguing that too wide a gulf between the upper and lower class has a negative effect on both classes and on society as a whole. You might, on the other hand, want to argue that Wells was critiquing Victorian faith in progress by showing a future society that was decaying, not improving. Whatever thesis you pick, be sure you have sufficient evidence, usually in the form of quotations from the novel, to back up your argument.