The principal currents in the conceptions regarding the course of history can be reduced to two.� One of them seen in history as a cycle or series of cycles that follow each other and, the other, sees an infinite straight line, without a beginning nor a foreseen end.� The concept of cycle is something very ancient and permanent in the human spirit.� In the Brahmanian theory, cycles form the calendar of the gods.� In ancient India the human year is made up of 360 days, without including the interpolated ones; the divine year is made up of 360 human years.� One Haha Yuga is formed by 120,000 divine years and is divided into four eras of unequal duration and similar rhythm.� An era is preceded by an ascending period and is followed by a phase of expiration; each one of them lasts one tenth of the principal era.� The Krita Yuga is composed of 400 divine ascending years, 4,000 divine years of a principal year and 400 divine years of expiration.� The periods of the Near East are nearer to the current concepts of time.� They are based on the direct observation of the stars, their interpretation of sacred books, cabalistic multiplications of the magic number, seven. One Jewish historian in Rome during the I century, Josephus Flavius, says that the most ancient times were divided into eras of 600 years.� Sirius� traslation movement of 1,461 years, that was the great astronomical discovery of the Egyptians, gave way to the appearance of mythological-historical conceptions on the sky.� Within this period of 1,461 years, not only the processes are repeated but also the lands, in the same order of succession.� Another Egyptian cycle has a structure similar to the Indian divine year.� It is made up of 36,525 years and it is said that once this cycle ends, the Golden Age will begin again on earth.� The Greeks have worked on this, they were searching for the �great cosmic year�, the rhythmic unit of universal evolution.� From the era of Plato comes the idea of a universal cycle of 700.000 years, after which everything begins again.� A later calculation to the II Century gives the universal year a duration of 9,977 earth years. The conceptions of Plato and Aristotle are also cyclical. For Plato the perfect number by which universal events are governed is the �cycle of that which is created by God�. At the same time it is converted into one of the fundamental laws of ethics. Aristotle reaches similar results through very different roads: the mathematical and physical reflection. He said that there is only one perfect and lasting form of movement, that is circular, such as is shown by celestial bodies with the greatest purity. The transformation of terrestrial things are nothing more than movements in circles that are more or less perfect.�