1. According to Islamic doctrines, acquiring religious knowledge and becoming familiar with the fundamentals of faith is everyone's obligatory duty. The Quran being the most important source of legislation calls on every individual to acquire knowledge as well as to contemplate and ponder.  To acquire knowledge of religious laws is also something which is not only recommended but he who gives up on it is condemned and reproached: "Why should not then a company from every party from among them go forth that they may apply themselves to obtain understanding in religion, and that they may warn their people when they come back to them that they may be cautious?"[1]
On the other hand, the instruction and training of learned jurisprudents began in the time of the Infallible Imams (AS) who at times referred people to their students and disciples There are a number of traditions in this regard as shall be mentioned below: When Imam Ali (AS) was in power, he instructed his governor of Mecca, Qasim Ibn Abbas, to be present in the morning and in the evening in the mosque and talk on religious edicts.[2]
This category of traditions makes it clear for us that until the occultation of the Imam of Time (atf), members of the community were referred to people other than the infallibles (AS) i.e. the disciples of the Imams. Here is a famous tradition from Imam of Time (atf) who said:

وَاَمَّا الْحَوَادِثُ الْوَاقِعَۃُ فَارْجِعُوْا فِیْھَا اِلیٰ رُوَاۃِ حَدِیْثِنَا فَاِنَّھُمْ حُجَّتِیْ عَلَیْکُمْ وَاَنَا حُجَّۃُ اللّٰہِ عَلَیْھِمْ.[3]

“And regarding the occurrence of new problems and issues, you refer to the narrators of our traditions, since they are my authority (hujjat) upon you as I am the authority of Allah upon them”
Based on this tradition, the people's duty during the period of occultation is clear. The "narrators of our traditions" in the above tradition are those, who because of being too much in touch with tradition and religious sources are competent enough to extract religious rules from their sources.  The religious authorities are experts in this field and it is quite rational and sensible for one to turn to an expert in every of field in all aspects and dimensions of our lives. It is not confined to the religion. Rather the position is the same in all fields and aspect of human life. For instance, every individual should either be a doctor or else he should visit a doctor for medication. He should be either a mechanic or he should turn to a mechanic for advice and help in mechanical affairs.
When it comes to jurisprudential matters, one who himself is an expert must not follow others in the same field. In fact, it is not permissible for him to follow others. However, he who is not an expert must refer to a learned jurisprudent because following a learned and knowledgeable person is rationally endorsed. God, the Exalted, also guides us to the same by saying:

«فَسْئَلُوا أَهْلَ الذِّكْرِ إِنْ كُنْتُمْ لا تَعْلَمُونَ»[4]

"Then ask those who know, if you do not know."
Imam Sadiq (AS) said: The scholars are the heirs of the prophets. The prophets did not leave any Dirham or Dinar (wealth) as their legacy but they did leave knowledge as their legacy. Whoever acquires a share from such legacy has gained a very large share. So see who you are receiving knowledge from.  Verily, among us (the Ahlulbayt) there are justice seeking people in every generation who safeguard our knowledge from alteration by exaggerators and doubts of those who cast doubt and the false interpretations of the ignorant ones."[5]
Also Imam Baqir (AS) has said: "Learn knowledge from those who bear it and teach it to your brothers as the scholars taught it to you."[6] 
2. Mujtahid is a jurist competent enough to deduce precise inferences[7] regarding the commandments from the holy Qur'an and the Sunnah of the holy Prophet by the process of Ijtihad. Ijtihad literally means striving and exerting. Technically as a term of jurisprudence it signifies the application by a jurist of all his faculties to the consideration of the authorities of law with a view to finding out what in all probability is the law. The laws derived from the sources are normally gathered in a book called "Tawzih al-Masail" (Islamic Laws). The religious authority who is a source of emulation must meet other conditions also such as piety, continence and awareness of the issues of the Islamic world and Shi'ism.
As stated earlier, taqlid in Shia religion began from the time of the Imams (AS) who referred their followers to the narrators of traditions as well as to their close companions.  Sometimes they even encouraged their companions to sit in the mosques and public places to give verdicts and guide people[8] which was due, mainly, to the fact that the people did not have access to the infallibles as they lived in other cities or in faraway places. During the period of minor occultation, there was a greater need for religious laws and, as per the narration which was related from Imam Mahdi (AS), during this time, people are supposed to know Islamic rules through the jurists who meet certain requirements. Thus, they should follow them and following such jurists is not confined to a particular time or era.
In the fourth Islamic century, taqlid was introduced as a technical term in the books concerning the principles of jurisprudence.[9] The first person to be known as a religious authority for elites and common people was Sheikh Tusi in the fifth Islamic century. That was why he was then called Sheikh al-Taefah (the scholar of the people). His juridical views drew attention from all other scholars.  There were some other prominent scholars before him in the fourth hegira century like his teacher Sheikh Mufid to whom people turned for advice in religious and spiritual matters. Also people like Ibn Abi Aqil Ummani, Ibn Wali and Sheikh Saduq wrote verdict –based books with reliance on narrations. They wrote fatwa books by mentioning the text of the traditions.  Sheikh Saduq wrote a book emulating a book titled "The Doctor of One Who Does not Have Access to any Doctor".  His book was titled "Faqih man La Yahzuruhu al-Faqih" which means "A Jurisprudent of Someone Who Does not Have Access to any Jurisprudent". 
Shiite scholars always considered themselves responsible and committed to deal with questions raised by Shia Muslims and even people from other Islamic sects. This practice never stopped at any period of time but it culminated in the time of Sheikh Tusi (ra). Because although answering people's questions was something routine and normal, the governments generally subscribed to Sunni beliefs and religion. Their books not only touched on general devotional practices and deeds but also they also dealt with particular and new issues until the opponents accused Shia of not having anything to say about particular and specific issues which caused Sheikh Tusi to write 'al-Mabsut'. [10] To respond to the blames and objections, he himself embarked on writing 'al-Mabsut' which deals with secondary jurisprudential issues. Given the prominence and greatness of Sheikh Tusi, for many centuries, the Shiite scholars benefited from his thoughts and views and no one ever wrote anything in opposition to him until Ibn Idris Hilli (ra) emerged in the scholarly circle.  He and the scholars after him showed the guts to challenged Sheikh Tusi's juridical notions.
Nevertheless, at the same time a book titled Sharaye' al-Islam was written and which is unique in its beauty and how it has separated secondary issues from main general topics. After him, the First and Second Martyrs (Shahidayn) emerged in the Shiite world. They wrote books like "The Gleam" (Lum'ah) and its "Annotation" in which they mixed the demonstrative jurisprudence with verdicts and made them available for the laity. In every period of time, there have been prominent jurisprudents who undertook the leadership of the Shiite community.  There haven't been any time in which people may not have had access to general religious authority ranging from Sheikh Saduq, Sheikh Mufid, Sheikh Tusi and Ibn Idris to Allamah Hilli, Shahidayn (Two Martyrs), Muqaddas Ardabili, Sheikh Bahai, Mjlisi, the First, and Majlisi, the Second to the scholars in the last few centuries such as Sheikh Ansari, Muhammad Hasan (the author of Jawaher al-Kalam) and many other scholars who like strong and formidable mountains served as refuge and shelter for Shiites across.
Indeed, during the Safavid period, there were some migrant scholars in the Safavid court. These scholars including Sheikh Bahai's father, Hussein bin Abdus Samad Amili (918 – 985), were from Jabil Amil[11] and who helped form a centrality in the clerical institution. Thus, scholars emerged whose reputation surpassed their region. It is not true to say that the Shiite marja'eyyah started in the Safavid era because, as stated, this is something rejected both textually and rationally.  Indeed, in the same way that the harmony and close ties of Sunni scholars with the governments of their time helped strengthen their position, the same is true with Shiite scholars who enjoyed an opportunity to strengthen themselves in the Safavid era. There was no such opportunity before this time and it does not mean that the scholars were affiliated to the government.[12] A look at what history tells us in this regard will make clear everything. A proof of that is the flourishing and emergence of Shiite scholars in every era especially during the stay of Ayatollah Boroujardi in the Islamic seminary of Qom.

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