Abdu’l-Baha describes an amazing journey in one’s spiritual transformation: the “school of spiritual progress” and the “branches of knowledge [that] will be developed” in “the university of heaven”

Thou hast described thyself as a student in the school of spiritual progress. Fortunate art thou! If these schools of progress lead to the university of heaven, then branches of knowledge will be developed whereby humanity will look upon the tablet of existence as a scroll endlessly unfolding; and all created things will be seen upon that scroll as letters and words. Then will the different planes of meaning be learned, and then within every atom of the universe will be witnessed the signs of the oneness of God. Then will man hear the cry of the Lord of the Kingdom, and behold the confirmations of the Holy Spirit coming to succour him. Then will he feel such bliss, such ecstasy, that the wide world with its vastness will no longer contain him, and he will set out for the Kingdom of God, and hurry along to the realm of the spirit. For once a bird hath grown its wings, it remaineth on the ground no more, but soareth upward into high heaven -- except for those birds that are tied by the leg, or those whose wings are broken, or mired down. (Abdu'l-Baha, Selections from the Writings of Abdu'l-Baha, p. 57)