All Amnesia demo discussion HERE

[superluser]

Question, if Daniel chose to drink the amnesia potion. Why was he frantically trying not to forget things like his name and where was from, and that he must stop Alexander. Isn't that what the letter you find is for?

A.) It could be that Daniel is unsure of whether he can count on finding the letter
B.) Daniel may think that it's important that this remains in working memory, not simply referred to.
C.) Combining the previous two, Daniel may be concerned that the letter might be compromised. Keeping the important elements in memory may act as a sort of validation that what he wrote is accurate.

or

D.) Daniel may have forgotten that he wrote the letter