The Passing of Time
Not surprisingly, given that two of Beckett's most famous plays actually reference the passing of time in their title, this is one of the themes that is returned to over and over again. Waiting for Godot alerts us to this passing of time in the title; the two characters are essentially waiting to find something that does not exist. However hard they try to stop it, time will pass for them just the same way it will for everyone else. Estragon points out that time "would have passed in any case" whether or not he and Vladimir had found some way in which to pass it.
Endgame is also a play that references the passing of time, as the title suggests, the characters have waited and waited whilst time passes to such a degree that they are now at the end of their time and faced with the realities of that.
Words and Language
The way in which language and words are utilized is almost an obsession with Beckett and this is why it is such a prominent theme throughout his work. In Waiting for Godot he expresses how language is given very little meaning and the way in which he feels people use words without weighing them with any meaning behind them. Pozzo orders Lucky to "think" but Lucky then speaks what is essentially garbled babble, showing that he does not understand any kind of meaning to the words he is saying at all. The work also expresses the way in which people have a tendency to talk constantly, thereby using language as a substitute for actual thinking.
The Accuracy of Personal History
In a number of his plays, Beckett touches on the theme of the unreliable narrator, only in the case of his plays, each character is an unreliable narrator in his own life history. He opines that people have a memory of their life that is not necessarily true. Certain things might stand out to them more than others until what they remember and what actually happened are quite different. He uses this theory in juxtaposition with other uncertainties, such as the present and the future. One cannot know what the future will be, which makes it completely uncertain. One might believe one is understanding the present but it needs to be viewed in retrospect to make sure that this was the case. Although it might seem that understanding our own past history is quite a reliable certainty, Beckett contends that this is not actually the case, and the theme is evident in both Waiting for Godot and Endgame.
