Or at least one of them, is Johannes Kepler. Like Linz’s least favorite son, Kepler wasn’t actually from there. Rather, he was born in Germany. Still he lived in Linz for quite some time, teaching mathematics and adding to his famous laws of planetary motion. Kepler did a lot in Linz, but the thing that captured my attention while I was reading about his exploits there this week was his participation in a debate about the adoption of the Gregorian Calendar.

Yeah sure Joe, sounds real interesting…click! Fine, but I’ve always found the topic fascinating — for what it says about the action of the solar system, but mostly for what it says about the all-too-common inaction of manmade political and religious organizations. For the Gregorian Calendar was officially instituted in 1582, but it took almost 500 years before it was finally, fully implemented around the world. And even today there are some holdouts.

Reader Jim sent me this exhaustive rundown of all the various American doughnut species, helpfully put together by folks at Serious Eats. There’s some pretty scary stuff in there, especially toward the bottom. Don’t say I didn’t warn you.

No, seriously, it doesn’t. Check this out. Thanks to reader Jordan for the tip — and the pun!

The main reason most Linzer tortes are made with short crust these days — or so I’ve come to believe — has to do with a certain technical issue. Reader Gerhard has convinced me that originally Linzer tortes were indeed cake-like and not tart-like, with red currant (or black currant) jam on the top.

But here’s the sticky detail: jam is gooey. It soaks into cake when you bake it on top of a liquid (or semi-liquid) batter. So how did the originators of the modern Linzer torte achieve a separation of the two? The answer: by applying paper-thin wafers to the batter and then spreading jam over them. Back-Oblaten they’re called…”baking wafers.” The jam goes on the wafer, the wafer provides a barrier and probably absorbs enough moisture from the jam during baking that you don’t know it’s there afterward.

See, according to the definitions I’ve advanced below, a Linzer torte — at least as I know it — is a tart. But if what Gerhard from Austria is telling me is true, that true Linzer tortes have a cake base, then the definition fits. I need to find a recipe for one of those. The one Mr. G sent me is in German, and my German, she iz no so good.

That’s an excellent question (thanks, Christine G.). The distinctions between cakes, layer cakes, tortes and gâteaux are rarely discussed. Most people simply assume they’re just different words people use to describe the same things, but that’s not really true. The distinctions between them can be fine but they’re real and worth noting. I’m not aware of any definitive resource on the subject, so all I can do is try to create my own. Pastry enthusiasts, chime in if you want to add or correct anything.

Cakes are single-layered sweetened and enriched “breads” for lack of a better word. Usually round and almost always flat, their primary ingredient is grain or grain flour (wheat, oat, barley or the like). Cakes can be sweetened with sugar, molasses or honey and enriched with eggs, solid fat or oil. They can be leavened naturally (yeast), mechanically (egg foam) or chemically (baking powder or soda).

…so whenever somebody finally succeeds after much trial and tribulation, I like to call attention to it. Julie over at Pass the Ketchup just turned out her first successful batch. As they used to say on Hee-Haw…sa-LOOT!.