For my 24th birthday (only 20ish posts ago–so goes my intention for frequent updates), I thought it would be proper to have a croissant and a hot chocolate. The trouble was that my neighborhood croissant supplier (only one at the time–this was obviously not in Paris) did not serve hot chocolate! So before striking out for my birthday breakfast, I heated up a cup, put it in a jar, and was kindly allowed to sip it in the café while simultaneously enjoying buttery, flakiness.

But the hot chocolate was not quite right. So, uncharacteristically, I gave up. Decided that I just cannot make hot chocolate, and will have to get my kicks from the professionals.

The story does not end there! It is quite cold here in Paris (may even snow over the weekend) and there is an abundance of good chocolate, so it is no surprise that hot chocolate is always on my mind (oh and let us not get confused about “chocolate milk” versus “hot chocolate”–“hot chocolate” should mean “chocolate melted in milk”–anything else is at best so-so, and not worth dreaming about). While bumbling around on the internet looking for recommendations for hot chocolate purveyors, I found a nice little recipe for hot chocolate. I didn’t take note of measurements, but I was piqued by the addition of sea salt. Oh, I thought, yes.


And that is how I learned to make my perfect hot chocolate. Here is the recipe: about 1/2 cup of milk, about 15 grams of chocolate (if more than 85% I also add a sugar cube), and a healthy pinch of sea salt (the salt I am using now is very coarse, but something finer would be…fine). Do you like my schizophrenic measuring system? You should listen to me talk about the weather.

Warm up the milk and salt. When it is hot add the chocolate. Stir all the while. When everything seems integrated, pour it all back into the cup you used to measure the milk (magically, through evaporation, it should all fit).

Of all the people I spend a lot of time with, there is one in particular who is very very deserving of a nice cup of hot chocolate: Jean Victor Poncelet (1788–1867).


After studying mathematics, Poncelet served in Napoleon’s army in which he went to Russia, got captured, and stayed for two years as a prisoner of war. It was so cold that the mercury froze (about -39 degrees Celsius) and he only had geometry to keep him warm.

Trust me, geometry is not very warm.

Nevertheless, Poncelet persevered and after returning to France published a Traité on perspective geometry, which I have been trying to wrap my head around for the past few months.

I imagine that such an experience leaves a permanent chill in ones bones. So I had Poncelet over for a chocolat chaud chat.

Immediately, he wanted to talk about his priority dispute over the invention of duality (a very cool thing–imagine it as a recipe where in substituting each ingredient for something else but maintaining the same proportions one would have a new and equally delicious dish).

No, no, Poncelet, I told him. Just let it be, nobody cares about who invented what first. In fact, it is decidedly unfashionable for historians to talk about that sort of thing. Besides, I reassured him, you have a street named after you in Paris, Metz, Chelles, and Saint-Avold. Gergonne only has a street named after him in Nîmes.

This seemed to greatly delight Poncelet, who may or may not have put a few drops of something stronger in his chocolate.

Now, I told him, you must explain to me your proof for the construction of the common secant between two conic sections where one is created by the envelope of one side of an inscribed polygon to the other.

Just read my book, he said, it’s all there.

Yes, in 400 pages I imagine it is.