There is no specific teaching of the Church about these things, other than to verify that the Communion of Saints and their intercession is real and true. Miracles are supernatural, or "above nature." The lives of the saints are liberally sprinkled and sometimes drowning in the supernatural. And devils, of course, exist. But, many supernatural events occur which aren't necessarily connected with any of these things. What are they all about?
My husband and I think there are five different categories of "ghosts." We've experienced them all to one degree or another, but (thanks be to God) most are the benign varieties.
1. Signal Graces: Signs from God through either His direct intercession or those of His saints. (St. Anne, St. Philomena, and St. Theresa the Little Flower have been very generous with us in this way.)
2. Demonic Forces: Very real. Very scary. They can only become a part of our lives to the extent God permits it, so we can at least take comfort in that fact. (Praise God, we've only had a couple of fleeting scares on this front, and pray to never have more than that.)
3. Human Souls: Those can be of the condemned variety (rare, we believe), souls in Purgatory seeking our assistance in releasing them from their sins, and those who have gotten trapped between this life and the next. Of that latter group, we know that "it is appointed unto each man once to die and then the judgment," but we know precious little about the specifics of God's judgment for us and the anecdotal evidence seems to suggest that it's not as instantaneous (at least not according to our sense of time) as we would think. It's one to wonder about for sure.
4. Residual or "Echo" Ghosts: It seems that intense emotion, strong personalities and life-changing events can leave a mark on a place, causing a moment in time to repeat. These ghosts don't communicate or react in any way with us, but move about more like a record with a skip in it.
5. Wrinkles in Time: Sometimes a ghost can be interactive, but does not appear to have a spiritual agenda, either good or evil. It's a theory of ours that time doesn't always work the way humans expect it to. We know so little about it from God's perspective. Could it be possible that our time overlaps with another one sometimes, and unexplained voices and things we see exist in real time, but not our time? We can only guess.
*Please understand these represent merely our theories, and do not reflect any teaching of the Church, whatsoever. We don't think they contradict any, either.
Most of our experiences, though, have been Echo Ghosts, and I'll tell you about some of those here, if you want to pull up a good thunderstorm and tuck in with a cup of cocoa and join me...In the first house my husband and I lived in (built in the '40s), we would periodically smel

l roast cooking in the kitchen. One time we came in the kitchen and all the cabinets were open, and none of us had done it. My sister had an apartment in the basement of that house. One night, hearing all the tramping and noise of us coming home after an outing, she came up to say howdy. But, when she came upstairs, we weren't there and the doors were all locked.
I seem to be sensitive to visual apparitions (this kind of sensitivity seems to run in my family), and glimpsed a man in blue cover-alls several times in and around the place. He seemed very sad, but moved about oblivious to us ~ just an echo of another time in that house, I'm sure.
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In our circa 1898 home on the Western Slope, I would catch a girl sitting on the fifth step from the bottom of our staircase every so often. She was wearing a long peach-colored dress and had her elbows on her knees, her chin cupped in her hands. She looked miffed. I've always wondered what event that recorded. Did someone stand her up?
Several times in that house I saw a woman in a long white nightgown go from one room to another, crossing the landing outside my bedroom door. She was going to the old nursery; we think she was probably a young mother who must have lived in the house many years before. Neither of these were ever scary to see, and were actually more of an interesting novelty and almost a comfort.
(I'm afraid we're not personally acquainted with the ghost pictured above.)
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When we first moved into this house ~ the old farmhouse on the high prairies, I was surprised to wake up one morning to an old lady in a rocking chair sitting next to the window in my room. She was there for just an instant and disappeared. I prayed for her soul and never saw her again.
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But the ghost we see the most often here at the farm is the young man in jeans and a cowboy hat. I catch him walking across the property fairly often. He's always outside.
One time, he was standing outside my bedroom window (which used to be the kitchen window of the house ~ incidentally, the same window near the old lady in the rocking chair). He was leaning in, as if he were getting ready to say something to me, with his hands braced against the top of the window frame, his hat pushed back on his head, wearing blue jeans and a blue shirt. He has much the same build as my oldest son, and, as I caught him out of the corner of my eye, I thought it was Paul ~ until I turned to say, "What do you need?" and he was instantly gone. That's how these ghosts are. Almost as soon as you realize you're seeing them, they're gone. But, since they're just echo ghosts, there is no feeling of fear that comes with them. I wish I knew who they were. I wonder if the young man was the builder of this house.
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One time I was sitting in the north room looking toward the big west window. The sun had just set, so it was dusky outside, but you could see a bit of reflection on the glass from inside. I saw what I thought was one of my children pass behind me, because I saw what I thought was their reflection in the window. I turned around to see who had come into the room, but there was nobody there. What I think I actually saw was an echo of someone coming out of the door that used to be at a right angle to the big west window. There's no door there now, and there was nobody outside. At least nobody but the ghost who had just come out of a walled-over door.
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My sister lived in a trailer on our property, just east of our house a few years ago. She's the member of the family who hears ghosts, while I tend more to see them. (Go figure that. We're an odd bunch, aren't we?) Anyway, Nina has told many stories of hearing people outside the trailer, when, after investigating, noone was there. (We live far from any other houses, the family was all accounted for indoors, and the animals ruled out, too.)

She was also the one who had someone sit on the end of her bed when she was sleeping in the old nursery in our last house (the one with the ghost mother in the white nightgown). She thought it was me or one of the kids coming in for some reason, and grabbed her glasses to see who was there. There was nobody there. Everyone else was sound asleep.
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When we were getting ready to move back to the prairie from the Western Slope, my husband delivered a truckload of paraphernalia back to the old farm. While he was here, he took a walk-through of the house. He was alone, standing near the base of the stairs, when he heard something thundering down the stairs.
It sounded exactly like our oldest children, who used to love to stampede down the stairs like a herd of elephants. Drove us crazy when we lived here the first time! He says he heard the noise and kind of rolled his eyes, not too surprised. No sense of fear at all. Is it possible that we have already created our own "echo" ghosts? Or maybe it was just a wrinkle in time window that opened up for just a minute.
Strange experience, regardless.
It's always just a little strange, to say the least, but, if you think about it, we shouldn't be surprised. We can't expect to have everything completely figured out. On many things we can only make guesses.
There are more things in heaven and earth, Horatio, than are dreamt of in your philosophy ...

A priest once told us that it is likely that anything evil would bring with it a definite feeling of evil and fear ~ most especially if we are in the state of grace. So, never having felt an evil threat, we figure, to cover all bases when faced with a ghost, it's good to say a prayer for the soul, in case it's a member of the Church Suffering, looking for help from us. That's the best we can do. We don't worry about it much, otherwise. But they make for interesting conversation! Who doesn't love a chance to swap tales and spin theories? Especially now that it's thunderstorm season on the prairies...
What are your ghost stories?
(There's a lot of
entertaining reading out there about ghostly encounters, but none are as good as first-hand stories!)