Now, in the Slavonic languages there are folk and poetic names for the months. Each nation has its own 'calendar', there is some overlap. 'Listopad' is in many of them, 'listopad' means 'leaves falling'. Now for some this is October, and for some it is November.
During the French Revolution, a Republican calendar, calendrier républicain, was created. A group of scientists, mathematicians, poets, a gardener, and a painter limned the epoch which began on 22 September 1792, the autumnal equinox and the proclamation of the republic. The second month of the Republican year would correspond to a convergence of the two Listopads; but no, our rational revolutionaries did not go for falling leaves, but for hanging fog (brume) Brumaire. We are now in year CCXXII (222). They decimalised the day, and the week, they replaced Saint days, with plant days. Calendars were long used as farming almanacs.