It's pretty neat that Memento is in alternating reverse chronological order.
But it's so much more than that. It's a complete philosophical assault on the the idea of memory.
Leonard bases his entire life off of Polaroids with notes written on them and tattoos, which leaves him susceptible to manipulation. However, Leonard is fairly confident of his ability to remain in control. He criticizes Teddy's notion of the importance of memories, which he says "irrelevant if you have the facts." Yet Leonard is the victim of constant manipulation.
As an audience member watching Leonard desperately try to cope with his constant lack of awareness, it is easy to feel superior. But how reliable is our own memory, even though it is intact?
In a famous study by Elizabeth Loftus, researchers convinced people that they had been on a hot air balloon as a child, even though they had not. In another study, participants were shown a video of a car accident. Using leading questions, the researchers were able to manipulate the person's perceptual memory of the accident. There have also been several (highly controversial) cases where psychiatrists have supposedly manipulated their patients into developing false memories that include rape, physical abuse and satanic rituals. This is in people with no previous memory issues.
Memento serves as a parallel to the issue of the reliability of our own memory. Leonard realizes he has a memory issue; but he believes he knows its root and he thinks he has created an effective coping mechanism. Not really, as you have probably found out.
But other than other people's unreliable testimony, Leonard has no way to verify his memory. In a similar manner, we don't have a good method for verifying our memory or who we are. In verifying our memories by talking to other people, we may end up changing our memories.
There is nothing more central to truth than our personal experience. Everything is interpreted through our own cranial lens, and the most effective way to manipulate someone is by making them believe that the manipulative beliefs are their own, much like a virus tricks its host into replicating viral DNA which the host believes is its own.
As we discussed after reading Aura, this course has followed a pattern of 'closing the distance' of truth. Cat's Cradle was the most far removed because it was outlandish, and Memento is the least removed, because it questions the reliability of self.
So how can we understand truth, if we don't understand ourselves?
The answer is simple:
Know Thyself.