In a second chapter in al-Ghazali's book, "The Jewels of the Quran", translated by Muhammad Abdul Quasem, he reflects on a saying of the Holy Prophet Muhammad, peace be upon him, that "The Sura of Opening is the key to Paradise." In al-Ghazali's words:
"At this point we (should like to) make you aware of a subtle matter. So we say that this sura is the opening of the Book (i.e. the Qur'an) and the key to Paradise. It is the key only because the doors of paradise are eight, and the meanings of the Sura of Opening (too) amount to eight. So know with certainty that each of of these is a key to one of the doors of Paradise. This is testified to by Tradition.
If you are such a one whose mind by chance does not have a belief in this (i.e. that the Sura of Opening is the key to Paradise) and yet you seek to understand the relationship (between the two), then abandon what you understood about the outward aspect of Paradise. (Should you do so) it will not be hidden from you that each meaning (of the Sura of Opening) will open the door of one of the gardens of gnosis (ma'rifa), as we have indicated in (our discussion of) the signs of God's mercy (May He be exalted!), the wonders of His works, and so on. Do not imagine that the repose of a gnostic (which proceeds) from / delight in the watery meadows of gnosis and its gardens is less than the repose of the one who will enter the Paradise which he knows and in which he will satisfy his desires for food, drink and sex. How can they be equal? On the contrary, it cannot be denied that among the gnostics there may be one whose desire for opening the door of gnosis in order to behold the kingdom of the heavens and the earth and the glory of their Creator and Disposer is more intense than his desire for women, food and clothing. How cannot the former be predominating in the discerning gnostic when it is shared with the angels in the highest Paradise, since they have no enjoyment in food, drink, women and clothing? Perhaps the enjoyment of animals in food, drink and copulation exceeds the enjoyment of men. If you consider sharing with animals and their pleasures as more necessary to seek than sharing with the angels in their joy and delight in the study of the beauty of Lordly Excellency, then how great are your error, ignorance and stupidity, and how lowly is your ambition! Your worth is in accordance with the worth of your ambition.
As to the gnostic, when eight of the doors of the Paradise of gnosis are opened to him and he (enters and) secludes himself in it, he will never pay heeds to the Paradise of the fools, since most of the people of Paradise are fools and the 'Illiyyyun' are indeed the possessors of intelligence, as is held in a Tradition.
O you who fall short (of the highest stage), your ambition for pleasures is also excessive and oscillating like that of animals! Do not deny that stages in Paradise are obtained by different kinds of gnosis. If the watery meadows of gnosis do not themselves deserve to be named Paradise, they (at least) deserve to be the means of obtainment of Paradise, and thus they will be the key to Paradise. Do not, therefore, deny that in the Sura of the Opening are to be found the keys to all doors of Paradise."
~ Excerpted from al-Ghazali's "The Jewels of the Qur'an" as translated by Muhammad Abdul Quasem, Ph.D (1977, pp. 73-74).