"In memory" vs "On memory"

[magicnumber9]

Why would one say "She prepared the words to impress them on her memory." As opposed to "She prepared the words to impress them in her memory"?
Or could both be used?
Thank you.

Does anybody know? I have class tomorrow.

[magicnumber9]

Any ideas?

[sonnet]

Both sentences are quite unnatural English.

However, in her memory is the more correct of the two - the first sentence is ungrammatical, I believe.

[magicnumber9]

Thank you for the reply.
I agree with your statement. I am currently teaching in China and a lot of the text books here have errors. This question was posed by a student to the head of our school who in turn asked myself. What I want to find out is why, in this sentence, one would say "on memory" instead of "in memory". I don't just want to answer "Because it sounds right!" What is the rule behind it?
Thank you.

[Lucy]

You're looking from the wrong angle. The preposition in connected to the verb and not to memory.

To impress on / upon

All the best,

Lucy

[magicnumber9]

Thank you.
So could one say "retain in her memory"?