Suffering
Suffering, while subtle throughout the majority of the film, is very much a major theme in the picture. Louise gains the ability to perceive the future through learning the heptapods' language, and by so doing learns of her and Ian's daughter dying at a young age. This is something she can change once she knows it by not marrying Ian or not having a baby, but she chooses to do so knowing the consequences. Her choice in suffering at the knowledge of her daughter's impending death is saying that life comes with suffering, it is our relationship to the pain and how we deal with it that can dictate the circumstances of our lives for better or worse.
Language
This theme is seen clearly through Louise's character and her journey to understand the heptapod language along with every other country. Language has the power within it to destroy or bring help. The film is quite clear that our interpretation of what is said to us can determine our response, and when we don't fully understand, as is the case with China, we often retaliate with force as we attempt to stop any impending violence with violence.
Time
For the heptapods, time is not linear as it is for humans. Their language allows them to perceive time in a non-linear manner which gives them the ability to alter their choices in the present moment to obtain a better outcome in the future. The film poses the question, "If you knew the future would you change anything?" We are all subjects of Time and what we choose to do with it is our own, regrets and all. As Shakespeare says in Richard II, "I wasted time, now doth time waste me". Louise's choice is hers in order to not regret in her life. The hardship of her choice is that she does not waste time, but because she knows the future time also wastes her as she moves ever closer to the day of her daughter's death.
Division
The theme of division can be found throughout the movie in the way countries relate to each other. Though at first the entire world seems to be working together in order to be able to communicate with the heptapods, it is made clear that this collaboration is fragile and tense. Furthermore, the disconnection between the nations is presented as the main conflict of the movie, as it is not until countries cut off communication - thus isolating themselves - that the tension in the plot reaches its highest point. Contrastingly, the first major breakthrough in the interaction with the heptapods is made when Louise and Ian remove their suits, hence taking down one of the barriers that divided the two species. While this gesture is fist described as a risk, it builds the basis to what would become a mutual understanding. After this event, the peak of the countries' collaboration is also shown, along with the progress that this leads to. Finally, the theme of division is further emphasized by the last message given by the heptapods at the Montana site, which contains the fraction 1/12. It is inferred that the information given by the aliens requires the 12 sites to share their information with each other in order to be useful, which in turn serves to reveal that one of the heptapod's purposes was to unite the different countries in order to receive help from Earth as a whole in the future. Therefore, the message of the movie through this theme is quite clear: division hinders progress, while unity is the path towards it.
Duality and balance
Louise and Ian embody the theme of opposing forces working together in order to create balance. This can be seen starting with the basic characteristics of each character: one is male, while the other is female; one works with a natural science (physics), while the other is specialized in humanities (linguistics). In fact, their first interaction constitutes a disagreement, which leads Colonel Weber to mention that this is the reason that they are both needed at the site. Moreover, the differences between Louise and Ian are further emphasized by the language used for each of their narrations. While Louise's is subjective, as well as filled with emotion and metaphors, Ian's is very systematic and contains a plethora of technical terms. However, despite their opposite way of thinking, it is clear that both characters need each other in order to succeed in the task of communicating with the heptapods. Finally, the theme of duality is reflected in the names given by Ian to the two heptapods, Abbott and Costello- a popular comedic duo characterized by the opposite personalities of each man.
