In a few corners of the internet, humankind’s propensity for organization is on glorious display. The Tumblr "Things Fitting Perfectly Into Other Things" and Buzzfeed lists like "29 Photos That Will Make You Breathe Easy" illustrate how neatly-set objects can induce sighs of happiness in millions.

There are bottle caps placed by many anonymous hands into the circles on top of a manhole cover, a Tic-Tac box inside a drawer compartment, and a vacuum head just sliding into a nook. But why does watching one object fill a niche in another feel so...right? Perhaps the feeling of comfort has roots in psychology, writes Julie Beck at The Atlantic — so she asked a few experts to weigh in.

“I think it has to do with a new way of putting things together in a surprising, novel, and exciting way. An unexpected way,” says Johan Wagemans, a professor of experimental psychology at the University of Leuven in Belgium. “Suddenly you see things in a different relationship and it challenges your expectations about how things relate to each other.”

Another expert tells Beck that the odd satisfaction may come from humans' need to find order in the world.

For a more in-depth look at the psychology of the perfect fit, be sure to read Beck's piece. But in the meantime, the very fact that the internet is here to bring you things like "Things Organized Neatly" might help fill the inner void created by a chaotic world. Fits nicely, doesn’t it?