Just as we can count the time through the chronological time, using clocks or calendars, we still have other types of time: the geologic time, refers to changes in the earth's crust, and the historical time which is related to changes in human societies.
Historical time has as its agents human groups, which bring about social change, while being modified by them.
Historical time reveals and clarifies the process by which the reality under study has passed or passes. In the 1960s, for example, in almost all of the West, youth lived through a hectic period, with changes, political movements, and opposition to governments. O rock, the hippies, the young revolutionaries and, in Brazil, Tropicalismo (Caetano Veloso, Gal Costa, Gilberto Gil, among others) and the Young Guard (Roberto Carlos, Erasmo Carlos, among many others), were social and musical experiences that gave to the decade of 60 a peculiar and different history of the 1950s and 1970s.
This is historical time: we draw a time limit to study its characteristic events, taking into account that at that chosen moment many human beings lived, dreamed, worked and acted on nature and other people in a specific way. .
History is not a prisoner of chronological time. Sometimes the historian is forced to go back and forth in time. He goes back to understanding the origins of a particular situation studied and goes on to explain his results.
The historical time count
The way of measuring and dividing time varies according to the belief, culture and customs of each people. Christians, for example, date human history from the birth of Jesus Christ. This type of calendar is used by almost every people in the world, including Brazil.
The starting point of each people in writing or telling their story is the event that is considered the most important.
The year 2008, in our calendar, for example, represents the sum of the years since the birth of Jesus and not all the time since human appearance on earth about four million years ago.
As we can see, the birth of Jesus Christ is the major milestone in the way we record time. Every year and century before the birth of Jesus is written with the letters BC and thus 127 BC, for example, is equal to 127 years before the birth of Christ.
The years and centuries that came after the birth of Jesus Christ are not written with the letters AD, simply write, for example, in the year 127.
Using the calendar makes life easier for people. Often, telling a particular event requires the use of time measures such as century, year, month, day, and even the time it occurred. Some commonly used time measurements are:
- millennium: period of 1,000 years;
- century: period of 100 years;
- decade: period of 10 years;
- five-year period: 5 years;
- triennium: period of 3 years;
- biennium: period of 2 years (so we talk about biennial).
Understanding Time Counting Conventions
To identify a century from any given date, we can use simple mathematical operations. Watch.
- If the year ends in two zeros, the century corresponds to the first digit (s) to the left of these zeros. See the examples:
year 800: 8th century
year 1700: 17th century
year 2000: 20th century
- If the year does not end in two zeros, disregard the unit and the tenth, if any, and add 1 to the rest of the number.
year 5: 0 + 1 = 1 century I
year 80: 0 + 1 = 1 century I
year 324 3 + 1 = 4 century IV
year 1830 18 + 1 = 19 century XIX
year 1998 19 + 1 = 20 century XX
year 2001 20 + 1 = 21 century XXI