“The stoneware vinegar bottle was Marie-Do’s sole culinary contribution to the house. Into it, she emptied the few trickles of red wine left after the dinner party. Inside, the mère, or mother, a gel-like colony of bacteria, transformed it into an aromatic vinegar. This bottle, with the mère already inside,  came to Paris in 1959 with Aline, the housekeeper hired to cook for Marie-Do, her young sister, and their widowed mother. Before that, who knew? Perhaps it had provided vinaigrette for a salad eaten by Napoleon. Julius Caesar’s cook might have used it to make that Roman favorite In Ovis Apalis, mixing vinegar, honey, and pine nuts as a sauce for hard-boiled eggs. As long as you kept it fed, the mère was immortal.”

The Most Beautiful Walk in the World- John Baxter.