The Drama of Sameness and Difference

I'm trying to find a satisfactory definition of ennui, something more descriptive than the "feeling of weariness and dissatisfaction" that Merriam-Webster offers up, and yet something that doesn't drag you straight down into a black hole populated with grotesquerie like Sylvia Plath's sonnet, "Ennui."

Something about a world drained of color should be in a proper definition, don't you think?

Even Walter Sickert's stark brown painting is a bit too colorful for this feeling, although I do appreciate the visual rhetoric of the half-full glass on the table (or is it half empty?). By the way, it is suspected that the artist, Sickert, might have been Jack the Ripper.
How about Asker Askerov's "Ennui"-- what the heck is going on here? A table topped with plenty of variety and goodness ignored by the listless woman at the table.
Here is a 16th century illustration of the health problem of ennui. A sad, bored person sits surrounded by books full of knowledge, cupboards full of curiosities and windows full of views.
I'm thinking that world-weary seems like a more adequate definition.

The problem is not with the world, of course. The world continues to spin thrillingly and to be populated with its usual glorious circus. It continues its usual pageant of sunsets, rainbows and synchronicity.

And yet, all of a sudden, the endless underlying patterns that other times offer comfort and orientation, suddenly just look like ... sameness. Same old sameness.

We need a little of both, I think. Some sameness to keep us oriented and comfortable, some difference to keep us interested.

There is probably a mathematical formula, a necessary balance that must be struck before we can feel satisfaction. I guess it's related to the usual tensions, such as that between order and chaos, rest and motion. But do we really need equal parts of each --difference and sameness --in order to be happy?

The problem, as I noted earlier, is not with the world, which continues to pour forth surprises as it always has. We're talking about a world that includes the Permian extinction event, mutating viruses and the platypus. It's hard to see how we could ever be bored.
Ennui is a problem with the way you're looking. It's like 3D glasses that makes some things apparent and others invisible.
We have this little thing in our brain called the reticular activating system, which is like a filter for what we notice and what we don't. It plays a role in language acquisition, which is how I learned about it. But I can't help wondering if it also plays a role in ennui.
Here's what I think:

In the wintertime, the world really does slow down, the colors really do drain right out, and our surroundings really are often limited by the weather. In wintertime, the world ceases its flamboyant displays; its beauty becomes understated -- all this just as the inconveniences of foul weather and illness set in.

If we want to keep ennui at bay in the wintertime, our reticular activating systems need to be in fine form and working overtime to see the difference-among-sameness that is the lifeblood of our satisfaction.

But how?

The scent of peppermint is said to stimulate this part of the brain. Some vitamin supplements claim to as well, for example, thiamine (found in wheat germ), and a synthetic form of B1 called sulbutiamine.

I don't know. It's worth a try. We have another two months of winter ahead of us.