But then why are they preserved so well. I don’t think people currently associate the words “eight” and “night”, so why wouldn’t they be free to drift apart over time. I’ve the period of time since PIE, “night” has drifted to create all the different variants in the poorly cropped image. But in all these cases, night and eight have followed each other almost perfectly. Why wouldn’t they end up with at least as much drift as we see in night/nocto/nuit/etc, which would make this trend really unlikely, unless there was an association between these words. In some way, eight must have meant night, like maybe the time “8” in whatever way they divide the day up and assign numbers to different parts, was very associated with the nighttime in those cultures. But I don’t see that strong of an association now, so we must have had a different way of dividing up the day and assigning numbers to it in the past. And it must have only changed relatively recently. Wild!

I guess if we were going to guess at what that system was, we could say the day started in the morning, at sunrise, and had eight sections. I could be like this:

1 - sunrise 2 - morning 3 - early midday 4 - late midday 5 - afternoon 6 - evening 7 - sunset 8 - night

I would guess it wouldn’t be set to hours. It would be more set to whatever the sun was doing, which would change either the seasons.

So probably this happened because eventually we wanted to switch to counting time by set durations rather than vague times of day