This article provides a short informative history of Nasir al-Din Tusi’s life, education and works. Nasir al-Din al-Tusi’s contribution to the post-13th century intellectual history of Islam is monumental, and many of his works became the standard in a variety of disciplines up to modern times. In particular, this article focuses on Tusi’s work in the field of Astronomy and his influence on the subsequent history of this area of the sciences.
via The Institute of Ismaili Studies – Nasir al-Din al-Tusi and Astronomy.
Ismailimail 
In his book “Nasir Khusraw, the Ruby of Badkhshan”, page 78 it is said:
“probing into alternate theologies left him unsatisfied unil he found out more about Ismaili interpretation of Islam. Ismaili doctrine appealed to him on many levels, most particularly in what he interpreted as its promotion of intellect and knowledge. In contrast, he says, to those schools which admonish believers to accept doctrines without asking questions, without probing in the ‘how and why’, Ismaili precepts cahmpioned human intellect as God’s finest creation.
Then on page 80, he continues:
Knowing the hidden meaning of exoteric things is comparable to hidden knowledge. Hidden knowledge belongs to God as He says in the Quran, 11:123, ‘To God belongs the unseen secrets of heavens and the earth’. So whoever knows more hidden knowledge is closer to God.
Also in the book “Nasir Khusraw, knowledge and liberation” on page 99-99 he says
“Thus if man has any sense he must learn and acquire knowledge by using the instruments (eyes, ears, heart and tongue)so that when he returns to the subtle abode which is his origin, he shall have with him something for the sake of which he was sent to this material world, and on the day he departs from here he should not be as he was when he came here. As God says, addressing the ignorant and unfortunate ones: ‘And indeed you have come to us alone as We created you at first at first, and you have left behind what We bestowed on you, (6:95)
-t SORRY CANT comp[let because of problem with internet????
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