The orthodox Muslim is bound by five sacred duties or "Pillars of the Faith". At least once during his lifetime he must be able to say with absolute conviction: "There is no God but Allah and Mohammed is His Prophet; he must pray five time daily, facing towards Mecca; he must give alms generously; if possible he must undertake the Hadj, the pilgrimage to Mecca; and he must keep the fast of Ramadan.
The holy month of Ramadan is the ninth of the Islamic calendar, and that of the Muslim year 1422 begins today. The complexities of the calendar allow Ramadan to occur at any time of the astronomical year. The pivotal date is July 16th, AD 622 by the old Julian calendar, the day of the Hejira or "Departure", when Mohammed, having incurred the displeasure of the merchant classes of his native Mecca, was obliged to flee to the neighbouring town of Medina.
Each Muslim year since the Hejira has consisted of 12 months, containing alternately 30 or 29 days. The first month is Muharram, the second Safar, and so on up to the twelfth month Dhu'l-Hijja. The ninth is Ramadan.
The commencement of Ramadan is governed by the moon. It begins officially at the instant when the thin crescent becomes visible again after the New Moon; that latter event took place yesterday, so the crescent will become visible to those with keen eyesight just after sunset this evening in those parts of the world where the moon happens to be above the horizon at the time.
In ancient times, official witnesses were sent to watch for this important event, and only when the formal report of their vigil had been received would the Holy Month be ushered in. Nowadays, of course, the exact instant of its occurrence is astronomically predictable.
According to Muslim tradition, Ramadan is the month in which the Koran was first revealed to the Prophet by an Angel of the Lord. Enshrined in that sacred text is the injunction: "O ye who believe! Fasting is prescribed to you, as it was prescribed to those before you, that ye may ward off evil".
Thus during the holy month of Ramadan it is forbidden either to eat or drink, or indulge in any worldly pleasure, during the daylight hours.
The obligation to fast falls on all Muslims except the very young, the sick and those engaged on arduous journeys, and lasts each day from the time when the light makes it possible to discern a "white thread from a black one" until the sun has set that evening.