Those who are steadfast in gaining science are the scholars whose knowledge will never vary until the day of resurrection. So, it is the divine prophets and the infallible Imams whose knowledge is a light excerpted from the light of God Almighty and is unchangeable.
The greatest of blessings and the most important of them is the blessing of lifetime, which is granted to mankind only once, and the petition of living one's life again will not be accepted neither in this world nor in the hereafter.