One of the best things about Waiting for Godot is that, although it seems to be a play about nothing, it provokes thought about many different themes and issues: everything from the pointlessness of life to the meaning of life.
The play concerns the nature of time as we experience it. As we live linearly, we are always moving into the future; therefore, we are always, in a sense, waiting for what comes next. Waiting for Godot plays with this idea, conjuring a wide array of possible implications, interpretations, and questions. In waiting for the more dramatic moments of life, are we missing the majority of life which is comprised mostly of "trivial" things? Is this life a waiting period until the next life? Is the play making a statement that we should not wait for an authority (God or human) for answers or guidance; that we should be self-reliant and/or existentialists?
Vladimir and Estragon are faced with an interminable wait. While they wait, they have trouble communicating, random things happen (including some violence), and in the end, they are still grasping with why they continue to wait. The play itself seems absurd, but these are also the elements of real life. We wait for things, random things occur which are beyond our abilities to predict, there is violence in the world, and we continue to have questions about humanity and existence.
This play raises a lot of questions about existence. A common theme/question is the issue of repetition. Vladimir and Estragon continue to wait, day after day. They realize the repetition, are aware that time has passed, and they struggle to make sense of the striking events and minor changes in their repeating days. Estragon flippantly says, "It's never the same pus from one second to the next." This, perhaps, is a reference to Heraclitus' metaphor of change and time:
No man ever steps in the same river twice.
In real life, we repeat things on a daily basis. We rarely question these "trivial" things because we are focused on the more important events. The same can be said for Vladimir and Estragon, to a point. They focus on Godot, but in becoming frustrated, they do begin to question why they wait; in doing so, they question the point of their existences. They struggle to find meaning in their lives, their waiting. They don't seem to come to any solid conclusions but the point is that they struggle.
The play raises more questions than it answers; this is one of the other great things about Waiting for Godot. Should they persevere and continue to wait or should they move on and focus on other aspects of their lives? What does "Godot" symbolize? The interpretations are endless.