The Romans inherited the calendrical system of the Egyptians, and followed a
365 day solar year. They separated the year into 12 months, which would have
either 29 or 31 days. Months with special holy days would have 31 (such as
Martius or Quintilis), other months would have 29.
It is from the Romans that we get many of the names of our calendar. The
word calendar in fact comes from the Romans. Kalends was the 1st day of
the month in Roman reckoning. Nones was the 5th or 7th day of the month,
and Ides was the 13th or 15th. (Nones and Ides would change depending on
whether it was a 29 day month or a 31 day month). The system of keeping track
of the months and the years became known as a calendar after Kalends.
The names of the months also come from the Roman calendar. The Romans began
their year in March, and the original names of the months were:
Martius Named for
Mars, the god of war.
Aprilis Coming from aperire,
which means “to open” in Latin, signifying the blossoming of the flowers
and the beginning of spring.
Maius Named for the
goddess of fertility.
Junius Named for the
goddess of the moon.
Quintillus 5 in Latin,
for the 5th month.
Sextilus 6 in Latin,
the 6th month.
September 7 in Latin,
the 7th month.
October 8 in Latin,
the 8th month.
November 9 in Latin,
the 9th month.
December 10 in Lation,
the 10th month.
Januarius Named for
the god of gateways.
Februarius A festival
of purification.
Two of these months would famously change names during the reigns of the
first two Emperors of Rome, where Quintillus and Sextilus would become July and
August. Both of these months have 31 days, because having 31 days signified
there was a holy day during that month. (One to honor Julius Caesar, and the
other to honor Augustus Caesar).