In short: Just as we saw by looking at the identity papers of an officer in our comparison that his rank, duty, wage, instructions and equipment prove that he exists not for the sake of some temporary battlefield, but rather that he is proceeding to some permanent kingdom, for the sake of which he is exerting himself — so too those to whom truth and certainty have been unveiled are unanimously agreed that the subtleties inscribed in the book of man's heart, the senses written down in the notebook of his intellect, the equipment contained in his essential character, are all turned towards Eternal Bliss; they have been given to man and fashioned in accordance with this ultimate goal.
For example, if one servant and illustrator of the intellect called "the imaginative power," is told that "you can have a million years of life and rule over the world, but in the end you shall become nothing," it will react with sorrow instead of pleasure, unless deceived by vain fancy and the interference of the soul. The greatest of transient things cannot, then, satisfy the smallest faculty of man.
It is, then, this disposition of man —his desires extending to eternity, his thoughts that embrace all of creation and his wishes that embrace the different varieties of eternal bliss— that demonstrates he has been created for eternity and will indeed proceed to eternity. This world is like a hospice for him, a waiting-room for the hereafter.
The Gate of Messengerhood and Revelation, and the Manifestation of "In the Name of God, the Merciful, the Compassionate"
Is it at all possible that errant doubts, no stronger than the wing of a fly, could close the path to the hereafter and the gate to Paradise that have been definitively opened by the Most Noble Messenger (Peace and blessings be upon him), with all of his might, relying upon the power of his thousand certified miracles as well as the thousands of decisive verses of the All-Wise Qur'an, a book miraculous in forty different ways — that Messenger whose words are affirmed by all of the other prophets, relying upon their own miracles, whose claim is affirmed by all of the saints, relying upon their visionary and charismatic experiences, and to whose veracity all of the purified scholars bear witness, relying upon their investigations of truth?