memory's capacity

[valentina_martin]

"The memory's capacity is virtually unlimited"
I found this sentence in a book for the First Certificate, but it sounds strange to me that it usese the saxon genitive when talking about memory. It must be correct but I don't know why. Thank you for explaining.
Valentina

[mykwyner]

The capacity belongs to the memory. It is just like the smile that belongs to your mother, your mother's smile.

The memory's inaccuracy has been well documented.
The heart's blood supply is very importand.
The scale's capacity has been exceeded.

Perhaps you are confused because, in this context, the noun phrase, the memory means a person's or one's memory, and not a specific memory.