Further to what shinny said, you SHOULD NOT memorise an essay AS IS. For example, if you're memorising an essay about encountering conflict using The Crucible as a reference, you should 'memorise' or 'reuse' the same linkages and references to the text, i.e. regardless of what the exam topic, you should be able to use your previous essays as a basis to which to write your essay. Here's an example:
Practice Essay Topic: "That conflict reveals the worst in people." So pretend you wrote the following passage in this essay:
"...Where they stand to gain from conflict, the greedy and selfish in any community often reveal their true colours, and manipulate the schism of society to maximise their personal benefit, regardless of the devastative effects on society. One such person, is Thomas Putnam in Miller's The Crucible, whose insatiable desire for land and power causes him to jettison his moral inhibitions to accuse innocent villagers of witchcraft to seize their property, revealing himself as someone driven purely by a materialistic selfish..."
Practice Topic 2: "That conflict is a natural phenomenon driven by an innate human desire for power"
The above passage could be changed to read:
"...For centuries, people, regardless of age, race or status, have fought over the need for power. With power comes assurance of one's success, fortune and future wellbeing. This human desire is exhibited in Miller's The Crucible, where a landowner's need for power and recognition surpass those for social and moral conformity lead him to accuse innocent others of witchcraft, so that he could acquire their land. Such selfish actions only serve to fuel the conflict which plagues the Salem community..."
Practice Topic 3: "Where humans are involved, conflict is inevitable."
Again some manipulation:
"...People have continually fought over land, an age old source of conflict. Given that people rarely give up land of their own free will, conflict undoubtedly results. Such a situation is played out in Miller's The Crucible, where a local villager Thomas Putnam, who has an insatiable desire for land, resorts to accusing others of witchcraft in order to seize their land. His jettisoning of social and moral inhibitions are only further indications that humans freely resort to conflict, if it means they are able to satify their own needs..."
So this is just an indication of what you need to be able to do in the exam, rather than regurgitate BIG slabs of info. (Plus don't bag what I just wrote, I have left English for about 6 months, so some of this may be grammatical incorrect and verbose or not fluent etc etc I wrote this on the spot just now).