well, that is my understanding of it too: man's relationship with nature!
What was it that your teacher say was missing?
Perhaps you just need an introduction to establish the idea clearly in your essay?
Anyways, heres a few intros that I've dug up from my HSC archives that I think may help: (these are intros from 18-20/20 assessments)
... presents a futuristic world that has been significantly affected by the progress of technology. However, this dystopian projection contrasts to Huxley’s world as he examines an environment that has completely deteriorated at the hands of humanity. Scott’s tension exists as a reflection of the rapid technological advancement occurring in the 1980’s.
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mine:
In trying to improve the natural state of man, both composers of Brave New World (BNW), and BladeRunner (BR) warn of the possible dangers of being disconnected with our natural state. In both texts, the composers are concerned with the advent of scientific and technological advances that may bring disastrous consequences, resulting in tension between mankind and his relationship with the natural world.
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... the advancement of technology has had unprecedented affects on the relationship between humanity and natural world throughout the century. Such affects have made the topic a regular issue for debate and analysis. The texts Brave New World (BNW) written by Alduos Huxley (1931) and Blade Runner (BR) directed by Ridley Scott (1982/1992) both address this subject. Through the aspects of control, domination of nature and class structure the affects of technology on humanity and the natural world are examined.
tell me if you want explaining. Good luck