They hadn't yet decided whether to count from 0 or from 1.

Surprisingly this comes up more then you'd think, for instance in Ancient Rome, tomorrow is two days away so all the dates are off by one from what you'd think it was. They mainly count down and it goes, 5, 4, 3, day before, day.

	▲	codebaobab an hour ago \| parent [-]
		I noticed that when I read Tom Holland's new translation of The Lives of the Caesars. All the dates were in the form "N days before Kalends/Ides".

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kps 2 hours ago | parent | prev [-]

“Should array indices start at 0 or 1? My compromise of 0.5 was rejected without, I thought, proper consideration.” — Stan Kelly-Bootle (first person to obtain a postgraduate degree in computer science)