What is a tessellation? For a long time, I got this word confused with tesseract, which I was introduced to by the novel A Wrinkle in Time (probably like everyone else who grew up before the Robert Downey Jr. Avengers era).

They are not the same. Tesseracts are four-dimensional hypercubes. Tesseracts are tiled repeating patterns that cover a surface completely without gaps or overlaps—think honeycombs or fish scales. Patterned floor tile or linoleum is probably the example most of us see every day.

The people who made up this holiday chose June 17 because it’s M.C. Escher’s birthday, and his art was big on tessellation-based artwork. I love Escher’s work; one of the fun things about college was all the dudes who ran around in Escher T-shirts. (Secret time: Another fun thing about college was the chance to do a lot of drugs and get really lost in those lithographs—or just wandering around campus and actually noticing just how many tessellations there are around us—leaf patterns, fencing, fabrics. Very distracting!!)

I’d never really thought about the prevalence of patterns before, and I pretty much stopped noticing them once I graduated, but I did maintain a love of houndstooth.

The other thing I never did was learn the math associated with these patterns. I was OK with geometry, but it was like learning a new language that I could get by in but never knew the vernacular or got the in-jokes. Trig? Forget it. My mathy friends tell me that tessellations are fun and easy, but then they start throwing around phrases like internal angles and radii, and I tune out.

Instead, I suggest you take a walk and look for patterns around you. Drugs are optional.