So, with the very kind permission of Athena (slightly abridged for reasons of space):
If you have never heard of a memory palace I would describe it as a physical place within your mind that you access during deep meditation. A memory palace can technically be any place. Some say you can use blue prints and construct your palace from that but I would instead recommend you use a place you actually know very well. I use my Great Grandma’s big rambling old home. No matter where it is you need to know it very well - as in going to the bathroom in the pitch dark with no night lights well - because it will allow you to access your way around with greater ease and will enable you to focus on the memories stored there. You really do want to know the memory palace like the back of your hand otherwise it’s kind of pointless because you will always be trying to figure out where something is and frustration is not conducive to the process.
The next step is to start stocking it with memories. You can use whatever you would like to hold the memory. An example in my memory palace - I have a lot of sculptures like Nefertiti and when I see that bust it holds the detailed memory of Egyptian artwork for me. On the other hand the painting of Venus de Milo holds a very detailed memory of a trip to Agate Beach with my family where I can feel the sand under my feet and feel the bite of the wind as it ruffles my son’s hair. The main thing is that the correlation works for you. Now that's just two small items in a huge house and suddenly you can see why the Memory Palace is such useful place. You can stock it with as many items as you would like and every candle stick can evoke its own vivid memory
To create your memory, focus on each and every detail including smells, sounds, textures… You want to create a immersive experience and the more you focus, the more complete the memory becomes. You may even discover things in the memory you didn't even think you could remember at first!
I have even added to my original memory palace. I added a barn with horses who are the pets I grew up with and here I can visit with my old friends, stroke their fur and smell the well oiled leather from my favourite saddle. In this way a memory palace can be a great comfort. However you can also choose to have a room to store blocked memories where you can carefully go through the unopened boxes of a painful past. Or you could shut the door on a recurring memory by shutting and locking the door so there it will remain until (or if ever) you want to deal with it.
One thing I do now when I'm in a “soon to be memory” is think how I want to remember the moment exactly. It might be a little hard at first to get started because you will have lots of flashes of memories that you want to store away but go slowly, treating each memory as the priceless treasure it is. I try to organize my rooms so like memories are stored together and in a way that makes sense to me.
You can get so detailed that you can even store memories in books so that the flip of each page invoke a different stored memory. The possibilities are endless - it's all a matter of how well you construct it and that you take care of it.
You can also use your memory palace to look into the future. I made a room specifically for crossing over to the spirit realm. My point is you should do what works for you, what triggers your own mind to go where you want it to. In this way you can build an amazing mental palace that's as real as any place in the physical world.
Since having this discussion with Athena I’ve been building my own memory palace. And she’s right – the total recall you can achieve in deep meditation is astounding. I’m using mine more for storing emotions and feelings and I have a room of absolute utter tranquillity (funnily enough, my Grandma’s old house, same as Athena) where I go in my mind whenever the world gets a bit too chaotic. And I like Athena’s ability to adapt as well, your mind doesn’t have to be limited by the physical world. My Grandma’s house used to be on a street but I think I might pick it up mentally and put it on some nice shady little island with gently lapping waves and leafy trees.
A memory palace is an excellent tool for a witch. We have a lot of remembering to do, a lot of what we need to remember is probably best not written down and we also spend a lot of time practising control with our minds, so taking mental organisation to such a structured level is not really a hardship for anyone practising the craft.