The Imam's Broad Field of Knowledge

Imam Reza (A.S.) had inherited the divine knowledge from his great grand father, the Holy prophet of Islam (S.A.W.).
The Holy Imam (A.S.) was practically like an ever-flowing fountain that quenched the knowledg seekers' thirst for learning. His holy father Imam Musa Kazim (A.S.) often advised the members of the family to consult with "Ali"[Imam Reza(A.S.)] about the problems they had in understanding the true concepts of the Islamic doctrines or about other religious issues. The Holy father enjoined them to learn by heart whatever "Ali" [Imam Reza(A.S.)] recommended.
Imam Reza (A.S.) was known as the wisest of all his contemporaries. His Holiness always succeeded in answering the questions raised by Mamun the ruling caliph with reference to the Quranic verses.
The caliph's official who was on duty to attend and escort the Holy Imam (A.S.) from Medina to Marv(Khorasan) narrates the following:
"I swear I could not find any person more abstemious and God-fearing than he was. On our way to Marv throngs of people rushed to welcome. His Holiness was requested by the people to give answers to their complicated questions in connection with different aspects of life and the divine creed presented and propagated by the Holy prophet of Islam (A.S.W.). The Holy Imam Reza (A.S.) related many traditions attributed to his forefathers. I reported the details of my personal observations to Mamun who in his turn approved of my views about the exalted status of the Holy Imam (A.S.), and confirmed that His Holiness was the best and the wisest and the most virtuous servant of God.
In order to explain the details of the divine knowledge bestowed upon the Holy Imam, one needs not quote the views of others in this regard.
A glance at the books on "Hadith" (the prophetic traditions) will help us to get acquainted with the rich words and discourses of Imam Reza (A.S.) uttered and delivered on subjects like the principles of Islam, the Isalmic ideology, the juristic issues, medicine and, the hygienic problems and many other subjects of Islamic research.
Mamun's perspicacity and his judgment of Imam Reza's vast extent of knowledge can be counted as proofs of the Holy Imam's competence in this regard. Historical records confirm that Mamoon the caliph was himself a celebrated erudite and his views were sound here.
In his official charter for the appointment of Imam Reza(A.S.) as his immediate successor Mamun points out the following statement:
"I know not any person superior to this man [Imam Reza(A.S.)] in the whole world."