Memory, wherein we recall past events, and imagination, which we use to visualize possible or impossible ones, are in some sense opposite yet complementary faculties of the human mind. However, the connection between the two is stronger than that, and Austen explores those interconnections in interesting ways.
A simple comment regarding Mrs. Gardiner's memory of the young Mr. Darcy is what first drew caught my attention to the way Austen is playing with these concepts. The passage below occurs at the end of Chapter 25--the him in question is Mr. Wickham:
"On being made acquainted with the present Mr. Darcy's treatment of him, she tried to remember some of that gentleman's reputed disposition when quite a lad which might agree with it, and was confident at last that she recollected having heard Mr. Fitzwilliam Darcy formerly spoken of as a very proud, ill-natured boy."
The language here is clearly meant to be ironic. Mrs. Gardiner may, in fact, have heard some talk of Mr. Darcy as a young man, but whatever she may have heard at the time was only recalled with great difficulty and is being filtered through her current, very warm feelings towards Mr Wickham and her belief in his story. And this, Austen is saying, is how memory actually works. It is not a photograph, as the simple metaphor would have it. Rather, whatever memories Mrs. Gardiner may, or may not, have about young Mr. Darcy are being manipulated by her current feelings towards him and Wickham. And what's doing the manipulation? Her imagination, of course, which is strongly influenced by her feelings. She's imagining something, and because that something is in accord with what she currently believes and feels, she ascribes to her imagined thing a reality, and it becomes indistinguishable from actual memory. Moreover, the fact that it is the very sensible, level-headed, intelligent Mrs. Gardiner who is the victim of the trick of memory strongly indicates that this is not the result of any weakness of mind, but rather that it is inherent to the human experience.
Another place with a striking interplay of memory and imagination occurs when Elizabeth enthusiastically responds to the Gardiners' invitation to join them on a tour of the northern counties and the Lake District. The passage below is from the end of Chapter 27 (emphasis mine):
"And when we do return, it shall not be like other travellers, without being able to give one accurate idea of anything. We will know where we have gone—we will recollect what we have seen. Lakes, mountains, and rivers shall not be jumbled together in our imaginations; nor when we attempt to describe any particular scene, will we begin quarreling about its relative situation. Let our first effusions be less insupportable than those of the generality of travellers."
Here, memory and imagination are explicitly linked by Elizabeth. Memory seems, here, to be the faculty for establishing the perception of a given moment or event, but it is the imagination which we use to retrieve it at a later time. But the imagination is a tricky, slippery things, capable of creating entire worlds that don't exist. If it is through the imagination that all memories (visual memories, at the very least) are accessed, how can we ever be certain that what we recall is an accurate reflection of reality? Indeed, Elizabeth acknowledges that most people's memories--or imaginations--fail them when they attempt to describe what they have witnessed. She seems to feel that this is a deficiency of mind, but as with the example from Mrs. Gardiner, I'm more inclined to believe this is because, even if the fact in question (the location of two items in relation to each other) is experienced identically by different people, it will be recalled differently, because the imagination will have its say, influencing our memories in small, or possibly large, ways. If Elizabeth and her aunt and uncle wish to be able to accurately relate everything they saw and never disagree, it is not sufficient that they have identical experience--they must have identical imaginative reactions to that experience.
The last example is not so much an example as it is a sort of gesturing towards something--a suggestion, almost. During Elizabeth's long and varied reaction to Mr. Darcy's letter, her feelings towards him and his goodness change radically. This change in feeling causes her to agree with some of his assessments of his family, and even to remember instances of behavior which support his case. The poor behavior of her younger sisters and mother was already plain to her; however, Mr. Darcy's letter encourages her to re-examine her father's behavior, and she must concede Darcy's point there, too. Is this, perhaps, an example of Mrs. Gardiner's experience with regard to her memories of young Darcy, but in reverse? In other words, had Elizabeth's love for her father been clouding her imagination enough that her memories of him were seen only hazily until Darcy's words--and her willingness to believe those words--lifted the cloud and allowed her imagination to produce the memory not as she saw it but from Mr. Darcy's arguably more accurate vantage point? Or perhaps even as it actually was?
I'll definitely be keeping a lookout for more instances of malleable memory as we proceed into Volume 3, coming soon, quickly to be followed by an introduction to our next Austen: Mansfield Park.