We have discussed about Imam Mahdi (p.b.u.h.) and his life , and now we should explain his Occultation, which is the most important part of his life .
“Occultation” means to be hidden and invisible , not “absent”. So by Occultation we mean the period of his life when people cannot see him but in fact he is present , lives with them and sees them. There are many Hadiths about it which all explain his being present:
Imam Ali (p.b.u.h) says:
“I swear to my God, (that) God’s proof is among people. He walks in the city, goes to their houses, and listens to them. He goes to the east and the west and greets them; he sees them but they do not see him until the promised time when God wishes.
Another kind of Occultation is also mentioned. The second special representation also mentioned. the second special representative of Imam Mahdi(p.b.u.h) say :
“Every year at the time of Hajj, Imam Mahdi (p.b.u.h) comes to Mecca. He sees people and know them, but they see him and do not recognize him “
So Imam Mahdi (p.b.u.h) has two kinds of Occultation. Sometimes he is hidden so that no one can see him. In other cases people see him but do not recognize him . In both cases he is present and lives among people .

Why Occultation?
Occultation has not happened for the first time in the history and just to God’s last proof. There are many Hadiths which show some of the prophets have lived hidden and out of sight. This kind of Occultation was not something personal but according to God’s will and in order to fulfill the divine tradition. In other words, the Almighty God ordered them to live in a hidden place and out of sight so that His expedience and will would be fulfilled .
Hence , we believe Occultation is one of divine traditions which had happened before to some prophets as Enoch, Abraham , Noah , Saleh , Joseph , Moses , Jethro , Elija , Solomon , Daniel , Jesus , etc. They had lived for some years out of sight so other people could not see them.
Therefore Occultation of Imam Mahdi (p.b.u.h) is one of traditions which previously many prophets had fulfilled and it should have been examined in his life as well. Imam Sadeq (p.b.u.h) says:
“Surely our Upholder has a Long Occultation. “What is the reason of his Occultation? “They asked. “For God wishes His tradition of his prophets Occultation to be fulfilled in his life as well. “He answered. “
Now another point is revealed , that many years before his time, other Imams and the holy prophet (p.b.u.t ) had talked about his Occultation , its characteristics and events which shall happen at the end of days . they also explained the duties of the faithfuls which should be done at that time .
The holy prophet (p.b.u.h) says:
“Mahdi (p.b.u.h) is of my offspring … he has an Occultation and leaves people in perplexity and distress and reappears like a falling star, when people go astray in their religion. He fills the world with justice as it is full of cruelty. “

The philosophy of Occultation:
What made our Imam and God’s proof on earth to be hidden and leave us here so that we cannot benefit form his reappearance?
There are many answers to the above question, but first of all let us mention one important point. We believe that he Almighty God has every thing, either important and big or minor and small, done according to His Omniscience and Wisdom, whether we understand the reason or not. In the meanwhile all major and minor events in the universe should happen just to His will. Hence, Imam Mahdi (p.b.u.h)’s Occultation, which is one of the major events in the whole history and universe, is due to a reason that just God knows and it is not important that we know it or not. Imam Sadeq (p.b.u.h) says:
“Surely our Upholder has an Occultation in which anyone of the wrong path shall doubt. “They asked about its reason. He replied: “We are not allowed to reveal its reason … His Occultation is of divine mysteries. We accept it , for we believe in God’s wisdom and His expediency , even if we do not find out the reason.”
However, while we consider all Divine actions reasonable and accept them completely, we can try to find out the mystery and hidden secrets beyond the Occultation in order to a sure ourselves and make our hearts firm in accepting Occultation. Here we mention four possible reasons which are pointed out in Hadiths of Imams (p.b.u.t) .

1. To punish people :
When people are not grateful to their prophet or Imam and do not carry out their grateful to their prophet or Imam and do not carry out their prophet or Imam and do not carry out their duties towards him or disobey him, God shall take him out of that society in order to punish them. When they do not value him , God hides him so in his Occultation they may recognize his value of being present . This is one of Divine reasons as Imam Baqer (p.b.u.h) says:
“When God does not like one of us [ Imams ] to be with our people , He shall take us away form them . “
2. To be independent :
Some, who try to bring about revolutions, have to ally with others in order to succeed in their effort. But Imam Mahdi (p.b.u.h.) tends to carry out his universal revolution and in his way to achieve this shall not collude with any cruel ruler, for according to many Hadiths, he is ordered to fight with any cruel ruler. he shall until the time of his Reappearance , so no to be obliged to collude with any one Imam Reza (p.b.u.h) says:
“[He shall be hidden] so when he comes with the sword of justice, he shall not owe to anyone any kind of debt. “
3. To test people [Divine Visitation]:
One of divine traditions is his visitation. he tests people in order to clarify their faith and stability in the right path . Surely he knows the results but he tests and shows them how their internal essence is. Imam Kazem (p.b.u.h) says:
“Be aware! When the fifth Imam after me disappears, be careful about your beliefs and no one makes you do so. He [Imam Mahdi (p.b.u.h)] shall disappear and some of his followers of his followers leave him and that shall be a divine visitation to distinguish people “.
4. To save his life :
For prophets, one reason to hide from their people was to keep their live safe and to continue their mission in a later time. However, all this hiding was ordered by God. Imam Mahdi (p.b.u.h) has been hidden for many years in order to be safe, just like the holy prophet (p.b.u.h) who hid in a cave when left Mecca at night. There are some Hadiths indicating this, as this – Imam Sadeq (p.b.u.h) says:
“Imam Mahdi shall be hidden for some years, before his revolution, because he is in danger “
Although any faithful servant of God wishes to be a martyr to his faith , he tries to fulfill his duties and be killed for God . Then , to avoid futile death , one may be afraid of being killed for no reason , which is logically correct . Hence , if Imam Mahdi (p.b.u.h) , the last proof of God on earth , dies for nothing , the pledge which is promised by God, and an event all prophets and Imams looked forward to its happening , shall be canceled .
Here we should mention that some other reasons have been considered and narrated as well but we keep the subject brief and do not bring them now . However, we should consider that “Occultation” is one of the secrets of God whose main reason shall be revealed when Imam Mahdi (p.b.u.h) reappears.