CONSTANTINE, the Roman Emperor who has been called "a great historical phenomenon," was a constructive statesman of boundless energy and daring, who saved a tottering empire. He came to the throne from distant Britain, where his father had set up a capital at York to govern the tributary provinces of Western Europe, including the areas which are now France, Spain, Germany, Scandinavia and the Low Countries.

His interest in the calendar stemmed from his tolerant attitude toward the Christians, who were a valuable part of his military and civil personnel. In Rome, the Diocletian persecutions of the Christians had reached a climax of inhuman cruelty, but Constantine was never a participant. Boldly taking the opposite side, he marched into his decisive battle against Rome with the cross of Christ on his banners and an inspired motto that "through this sign thou shalt conquer."

As Emperor, he did not make Christianity the sole religion of the state. To the end of his days, he bore the title Pontifex Maximus as chief priest of the ancient pagan Roman hierarchy. But at the same time he gave Christianity complete equality with the traditional official worship. The coins which he issued carry both the cross and the images of Mars and Jupiter. Personally, he leaned more toward the Christians and on his death bed became one of them.

He had always been impressed with the Christian ideas about the calendar. He liked their observance of a seven-day week, with the first day set aside as a day of rest and worship. The week was a complete novelty to the Roman calendar, which had its months subdivided into the impractical Nones, Ides and Kalends,

Nine years after Constantine became Emperor he issued an edict introducing the seven-day week into the Julian calendar. The weekdays had no names but were known only by numbers. The week displaced the old Kalends, Nones and Ides, and eventually the days acquired the names of the seven heavenly bodies--Sun, Moon, Mars, Mercury, Jupiter, Venus and Saturn.

Unfortunately, Constantine in introducing the week did not give the matter the full scientific consideration it deserved. He did not realize that he was removing from the Julian calendar the perpetual characteristic which had been one of its chief merits. Julius Caesar had established a calendar that was exactly the same year after year; even the bissextile observance in leap year did not disturb the perpetuity of the calendar. But now, with the new seven-day week gradually gaining outstanding importance in time measurement, the Roman calendar lost this desirable perpetual feature. The weekdays rotated, and every year became different from the preceding and following one.

The change must have been annoying to the Romans and all their satellites, from Britain to India, because the monumental permanent calendars which had been erected in every part of the empire--carved in stone--had now become useless. In adopting the week, the imperial authorities had not given any considerations to the fact that 52 1/7 weeks within a 365-day year would involve difficult adjustments and recurring confusions. They carelessly thought of the year as 52 weeks; but the period of 52 weeks was always short a day to complete a true solar year--so at the end of each year a day must be borrowed from the first week of the next year. The New Year could never begin consecutively on the first day of the week. The perpetual calendar was lost.

Had Constantine foreseen the effect of his action, he probably would have made adjustments. The device of intercalation was familiar in many regional calendars of his contemporary world: for example, in Egypt, Greece and Palestine. He might easily have hit upon the idea of a supplementary day without a weekday name, and thus he could have preserved the entity of the year which had been so carefully maintained in the Egyptian and Julian systems.

Thus the wandering week became the chief difficulty with the calendar, a serious defect that has continued ever since, and one that will be remedied at long last with the adoption of The World Calendar.

The origin of the week is historically a question that goes back further than any existing record. It was introduced into Palestine from the Assyrians, who used the seven weekdays as symbols for the seven heavenly bodies which were the basis of their astrology. The astrological belief was that each hour of the day was governed by a different "planet," in the order of their supposed distance from the Earth--Saturn, Jupiter, Mars, Sun, Venus, Mercury and Moon. The "planet" which governed the first hour of the day was called its Regent. If the Sun was regent for the first day, then the regents for the following days were: Moon, Mars, Mercury, Jupiter, Venus and Saturn--the same order of days that we observe in the week today. (In the Teutonic languages we have replaced the midweek deities with their counterparts--Tiu, Wooden, Thor and Freya.)

But further back than the Assyrians, it is probable that the seven-day week was related in the earlier lunar calendars to the four phases of the moon, each about seven days in duration. Actually there were several kinds of "weeks" used. The early Romans observed an eight-day market week; other tribal and primitive people had market weeks of four, five or six days; the Egyptians and Greeks divided their months into ten-day periods.

Whatever its origin, the week with its one day of spiritual observance has proved a time unit of profound significance and high value to the human race. Through Constantine's decree the week received its right beginning, Sunday, observed by the Christians in commemoration of the Resurrection, and its right ending, Saturday, honored by the Jews and Seventh-Day Adventists as the sacred day of rest. A deep significance has ever been attached to beginning and ending the week on the highest spiritual note. Friday remains the religious day of the Moslems, the Hegira, when Mohammed was forced to flee from Mecca. Even those for whom the week has no religious connotation would not think of abandoning the seven-day week, an interval of Time that fits perfectly into the spiritual and practical living of peoples everywhere. The inherent benefits of one day of rest and worship are universally recognized. Mankind and the calendar are enriched and ennobled with its observance.