Any day visiting this city is likely to be a good day, but I believe it becomes an iron-clad guarantee if at some point you walk onto the Ile de la Cite and the neighboring little Ile St-Louis.

The former is the heart of the city, and has many of its oldest buildings, including the Notre Dame cathedral. The rest of the island is pretty much devoted to government buildings. But the eastern end of the island has some kitschy shops, and the Esmeralda tavern — and the little park I like, and the monster church, and lots of smiling and grinning tourists snapping photos and moving on their way.

Ile St-Louis, just across the middle arm of the Seine, is such a compact little gem, quiet but well-to-do, with high-end housing and some interesting shops, too. If money were no object, I might well choose to live on the little island.

I feel my spirits raised when I walk onto those two islands. It could be the guys with accordions who sit on the bridges (see video, below), especially on the Pont St-Louis which connects the little island to the bigger. (Though the Pont Louis-Philippe, connecting St-Louis to the Right Bank, is far the older of the two bridges.)

You can’t be moody or depressed, while listening to an accordion. It’s like a banjo. Steve Martin, the comedian, observed that you just can’t get mired in dark thoughts like “death and destruction” while listening to a banjo. Same with an accordion. (Though enough time listening to either instrument can set a person’s nerves on edge. Yes.)

The islands have another up side … which is the likelihood of them being sunny — because of the unobstructed expanses on either side of them created by the Seine. If sunlight is actually going to reach the ground anywhere in the heart of Paris, it will do so on one of the city’s two islands.

I don’t often do much of anything on the two islands. I jog or walk on Ile de la Cite, and sometimes circle around to the front of Notre Dame. And I do little more than buy Berthillon ice cream out a window on Ile St-Louis.

I think that might be the feel-good secret of the two islands. Most people aren’t actually going anywhere, when they are on both islands. They’re just hanging out. Looking and watching and soaking up the atmosphere. To be on those islands means no rush. It means good times.

They offer a sense of removal from the hectic world on either bank of the river … that never fails to make me smile.