For such an expectation it is necessary to have an exact knowledge of the promised figure.  So  that  we could not mistake him with the dolls of the puppet-shows of the powers that sing a new song every day in order to break up and destroy the wonderful epic of expectation, nor could the extra­vagant talks of ignorant and self-interested people cover up this matter with a veil of superstitions, and thus change our hope into despair, and our longing into defeat.

He is the twelfth and last leader of the Shia society of Muhammad, a son of Imam Hasan Askari, born in the middle of the month of Shabaan of 255 of the Hijra. His fine mother was Narjis, a Roman lady who was converted to Islam and had become Imam Askari's consort.

The true and great Shia leaders have, on sorrowful occasions, given their friends the tidings of his advent.  When Imam Hasan Mojtaba was compelled to make peace with Mo'avieh and was reproached for it by some people, he offered several reasons for the correctness of his deed, of which superficial people were ignorant, and said:

“Did you not know that there is no Imam of ours who is not forced to show allegiance to the arrogant men of his time except the concealed and awaited Imam behind whom Jesus performs his prayer? Then, as God indeed conceals his birth and hides him from people so that, on his reappearance, he could owe allegiance to no one, know that he is the ninth offspring of Hussein, my brother's generation, and son of the noblest slave-girl. God will give him a long life in his absence and then, by His might, He will let him reappear as a young man under forty in order to show that God is mighty in everything." (32)

Since it was God's will that Mahdi should be secure against enemies' harm and be able in future to carry out the great plan of setting up a single world government based on justice. He disappeared from public view, when in 260 of the Hijra, Imam Askari, his father, suffered martyrdom, and he had performed the prayer rites for his father's corpse. The reason is that the tyrannical Abassid Caliphs knew, on the strength of the tidings given by the prophets and previous Imams, (33) that he would break up the whole system of the wicked based on oppression and crimes. So they were seeking his death, and after the above-mentioned burial ceremony, they rushed to his house to kill him.

He was hidden from public sight for seventy years from that date onward, and only the select Shias of the Imam were allowed to meet him, and explain the difficulties experienced by themselves and others. Those men were given the name of the select deputies' in Shi'a history and this period of seventy years was called 'the short absence'.

At that time when some wicked individuals thought of communicating with the Imam for the purpose of misleading the people, the Imam, in a letter in his own handwriting delivered by his fourth deputy, announced the question of deputy ship and declared all communication with himself terminated until his reappearance.

In this period which is called   “ long absence", the Imam lives incognito among people.  And as it is mentioned in Shia traditions and narratives he walks about markets, steps on people's carpets, and they see him without recognizing him.  Whereas he sees and recognizes them, and this state is considered similar to that of Joseph and his brothers, (34) for the people saw Joseph a ruler of Egypt and talked with him, but were unable to recognize him, while Joseph knew them all.

In this period, Imam Muhammad-bin-Hasan, in cases of need, defends the religion as an ordinary individual and solves the difficulties of the Shi’as And whenever necessary, he introduces himself to a trustworthy Shia who can guard a secret and issues orders to him. It is a belief in these helpful acts of Imam Mahdi that gives the Shia a remarkable courage, and by reliance on such assistance, they resume their fearless combat against falsehood howsoever strong it might be. This state reminds one of the saying of Imam Ali who says:

“By reliance on the presence of the Prophet in the hardest moments of the battle, we did not withdraw from the scene and continued to fight till victory was won " (35)

During the period of Imam's absence, the Shia act to receive religious edicts in the same way as in the periods when other Imams were living. This means that similar to the time when the Imam sent for them an honest scholar and expert in religious matters to submit their questions to him and learn their duties from him. While most of them never met the Imam even once in all their lives, in his absence, too, the Shias are dutybound to approach to their religious scholars who are protectors of religions, never follow their whims and fancies, and only obey God's commands given in the Quran and tradition. (36)

But, on his advent, all human beings follow the religion of Islam, Muhammad’s faith and the Book of God, and act on the instructions issued by Imam Mahdi. To explain this point further, we refer to the words of the leader of the Shias who says:

“The concealed Imam will invite the people to my faith and to follow the Quran’s in functions.” (37)

 “In  his government of the world, there will remain no land in which the call of faith, God's uniqueness and Muhammad's Prophethood  is not heard." (38)

 "Mahdi will establish the Islamic prayer and will himself act as its Imam. (39)

 Imam Ali  the first Imam of the Shi' as, says:

 "The concealed Imam will, on his advent, offer Islam to people and calls upon them to follow it." (40)

Imam Baqir, the fifth leader of the Shias, says:

 "The concealed Imam will begin his task at Mecca, and will seek people's allegiance on the basis of faith in the Quran, the Prophet's ways, his own guardianship, and dislike of his enemies." (41)

He says also:

"In the government of Mahdi no one remains without having joined the followers of Muhammad." (42)

It is under the auspices of this program that Islam which has been forgotten and the Quran which has been laid aside, will be brought back to the people's life.    The society will be built up on the basis of the Quranic injunctions; a new life will be given to Islam and Muslims, and the glorious rule of the Quran will be revived. And this greatness will be so noticeable that the people will find it hard to believe that they have attained that sublimity through the Quran which they possessed." Imam Sadiq says about Imam Mahdi's program:

"Mahdi will do what the Prophet of God did, that is, he will do away with the existing innovations in the same way that the prophet destroyed paganism, and then he will rebuild Islam." (43)

The Prophet says about Mahdi's uprising:

"A time will come when Islam is left only in name and the Quran becomes a mere formality. Then God will permit him to rise up and with his assistance, Islam will be strengthened and renewed.”(44)

Therefore, as the other Imams did not introduce a new religion, but only revived and strengthened Islam.   Imam Mahdi, too, will act as Imam on the basis of Muhammad's religion. And will not even hide his belief against enemies for the sake of a greater expediency, but he will declare his mission openly from the very outset. According to the words of Imam Sadiq, hiding one’s faith will not only be forbidden for him but also for all his followers at the time of his advent, (45) because such a covert act is required in difficult circumstances or in the eventuality of any damage to Islam, and these factors will be non existent  since his advent is the beginning of relief and ease.

Reflection about the question of absence clarifies certain facts, the way to realize which is the Imam's absence in itself. For example, the only way to reform those individuals who preferred their whims to the logical reasoning of the prophets concerning the necessity of following religion.   Or created or adhered to various schools of thought and ideologies inspite of the clear utterances of the prophets about the inability of man in the matter of legislation, is to practically prove this fact that man-made schools of thought produce nothing for mankind.  They only create confusion and distress, and if someone seeks happiness, he should obey the orders of the prophets. Moreover, those who, inspite  of clear evidences and signs, lose their identity in the face of knowledge and suppose that knowledge can re­place faith, should discern this point that knowledge acts only as a means, and the mode of its utilization should be determined by religion, otherwise it may cause the greatest damage to mankind.

The period of the Imam's absence is the phase of leaving man to himself, so that by not following nature and reason, experience proves to him that human society is always in need of divine guidance. As the leaders of Islam have declared, the advent of Imam Mahdi takes place at a time when the majority of human beings wholeheartedly desires divine guidance to be liberated from the disorders and confusions that have been created by itself. And seeks the establishment of a society on the basis of the Quranic laws. That is why we see that there is a constant increase in the number of thoughtful beings who are aware of the need for religion and admit it.

In addition to the above matter, during this period of absence, the Shias are tested for their steadfastness in religion. As this period is long, and infidelity may dominate faith. And add to the commitment of sins and oppression, as well as indulgence in carnal desires, the Shias are subjected to a constant trial so as to differentiate between those who verbally claim to be believers while in comfort, and those who are true believers.

We find both these points concerning the subject of Mahdi1s absence in a brief utterance of Imam Sadiq who says:

 “This matter - the Imam's  advent and uprising - will not take place until after despair of finding happiness through man made schools of thought or by virtue of the victory of Islam on account of the lengthy wait, Nay! I swear to God that it will not come until you believers are separated from hypocrites. By God, it will not come until the miserable become truly miserable, and the happy truly happy.”(46)

He says also:

“As  the absence period is long, only one group remains steadfast, and a group of other people say '1He is not yet born! II Others say: “He was born and then died" Some say: “The eleventh Imam had no offspring." Others commit sin by saying "The Imam is incarnated in another body and then speaks." (47)

This question may arise that if the reappearance of Imam Mahdi takes place many centuries after his father, Imam Askari, why, then, was he born in the lifetime of his father to remain unidentified for such a long time?  In response, we must point out that according to the Shia belief which is based on the utterances of Islamic leaders, the world never remains without evidence. Namely, in every era, there must exist a perfect human being who has known God in the most perfect way, and has obeyed and worshipped him in the worthiest manner.

Imam Ali says:

"The world will never be devoid of evidence, whether it is known or unknown." (48)

 Also Imam Sadiq says:

"If there are only two people left on the earth, one of them will be the evidence." (49)

"If there were no evidence of God, the earth and its inhabitants would be destroyed." (50)

 Thus, we see that the world never lacks evidence. But according to the utterances of the Prophet and Imams, the evidence of God next to the Prophet himself is presented by the twelve Imams. As an example, an utterance of the Prophet is quoted below, saying:

"Indeed, the deputies and evidence of God after me are twelve people, the first of whom is Ali  and the last is Mahdi."  (51)

In view of the above two points and also the fact that history gives the exact details of the life and death of these Imams, there is no alternative but that after the eleventh Imam, there should exist Mahdi as God's deputy.  Henceforth, to show the continuity of existence in the world.  Moreover his program requires preliminaries, some of them mentioned before, for which the passage of many centuries would be necessary, and thus Mahdi must have a long life.

It, therefore, becomes clear that the need for evidence and continuation of the world's existence, and the fact that there remained no deputy but Mahdi after the decease of Imam Hasan Askari, leave no alternative but Mahdi as a living evidence on the earth after his father's death. And until the time he (Mahdi) reappears.

Another point which may seem obscure is the life-span of several centuries of Mahdi as stated in various traditions and narratives and considered as one of Mahdi's characteristics.

As an example, we will quote a few of the words of the Shia Imams related to this matter.

Imam Sajjad says:

“In Imam Mahdi, there is a quality of Noah and that is the length of his life-span" (52)

Imam Reza says about Mahdi:

"He is of a long age and has a young face, and an observer may take him for a man of forty or less and another sign of his is that he does not grow old until God's command is issued." (53)

To clarify this matter, it should be remembered that if we recognize God to be All-Powerful. Every difficult and extraordinary thing is possible for Him if He desires so. And in view of the role of Mahdi in human history which is the consequence of the ceaseless endeavor of the prophets, it is reasonable to believe that God will keep him young and powerful until Resurrection time.

Moreover if we regard this matter scientifically, we realize that the present-day knowledge does not only not fix a limit for human life span, but what it considers natural is very a long life.  If we are witnessing the short life of human beings, it is due to the fact that man is not aware of the mechanism of his existence and does not know its proper use. Consequently he is every moment faced with great losses which damage his body and spirit. Therefore, with the advance of knowledge and man's greater awareness of his own mechanism, his life span has continued to increase. This is clearly shown by age  statistics of human beings.

As an example, in England the average age of men between the years 1838 and 1845 had been 39.91 years, and that of women 41.85 years. In 1937, the average age of men had risen to 60 and that of women to 64.   Similarly, in America in 1901 the average ages of men and women were respectively 48 and 51, while in 1944 these had gone up to 63.5 and 69. (54)

Learned men of today have discussed the longevity of human beings in different ways, some of which are given here as example:

The German scholar, Weisman, says:

"Death is not necessarily a law of nature, and in the world of nature, there is eternal life as well as a momentary one. What is natural is an everlasting life. In our own time, man’s life span has increased, and there is no reason why it should not continue to rise and allow a human being to live nine centuries.” (55)

 Yuri Fialkov, professor of technology at Kiev in the Soviet Union, says:

"An Atom which forms the basis of matter is eternal and is never destroyed by itself provided it is not done so by outside forces.  The cell, too, which is the basis of living creatures is eternal on condition that it is duly fed and is not destroyed by extreme cold and heat.” (56)

 He says also:

 “Man should live forever  and never die, for, a living cell is eternally alive." (57)

Jean Rostand, the well-known biologist, says:

 "I admit that there exist natural factors of aging in a human being, but many of the bodily cells are not destructible, and it is not right to say these eternal cells assemble to create a mortal body." (58)

Attention to these matters shows that modern knowledge does not only reject the idea of a long life span  being incompatible with the mechanism of creation of man, but also regards a short life as unnatural.

History, too, is a true testimony of man's length of life, and tells us of those who have lived long, such as Noah, Elias and Methuselah, (59)as well as others mentioned in other books. In our own times  we have heard of ages several times that of ordinary life spans such as a 207-year-old man of south America, (60) Sayed Abu-Taleb Musari Farsi who lived for 101 years;(61) Muhammad Baqir Oghlu of 184 years; (62) Shir Aliov of the Caucasia 168 years of age;(63) Hatin Nin, a Turkish woman of 168;(64) Luisa Trosko, a woman of 175; Teps Abzip of 180; and Sayed Ah Kutahi of 185.(65)

The only point that remains is the small number of people with a long life. But it must be remembered that the rarity of matter is not an evidence of its impossibility in the same way that geniuses rarely appear, but this does not mean the absence of great talents of such men as Edison, Einstein etc.

Thus, the question of Mahdi's life-span, in addition to its being the wish of God and in view of His absolute might, and therefore practicable, is also possible from the viewpoint of modern knowledge as is confirmed by various testimonies.

The above discussion shows that the world is in need of a savior and awaits him. This expectation, in its most genuine form, figures in Shiism as a revolutionary principle, and the leader of an Islamic world government., who will rule the world on the basis of the Quran and traditions, is none but Muhammad, son of the eleventh Imam of the Shias, who was born in 255 of the Hijra, and lives incognito amidst people, He has been given a long life by God in order to reappear when the world is ready for the rule of the Quran, take over the world affairs and fight oppressors.