THE HEAVEN OF THE MOON.--They are received into the eternal pearl of the Moon (_Par._ ii.); where Beatrice first confutes Dante’s former theory concerning the luminous substance of the celestial bodies, and, by explaining how everything in the visible world depends upon the angelic movers of the sphere, gives a mystical interpretation of a natural phenomenon, on this first step of his ascent to the suprasensible. Within this eternal pearl appear faint but divinely beautiful forms of women; the souls of those who had yielded to violence and broken their solemn vow (_Par._ iii.). Piccarda Donati, sister of Corso and Forese, sets forth the perfection of celestial charity, where all wills are made absolutely one with the will of God, who has awarded different degrees or mansions of beatitude to all His chosen ones: E la sua volontade è nostra pace, “And His will is our peace.”[38] Transfigured now with ineffable joy, Piccarda tells the pathetic story of her frustrated life on earth; and points out to Dante the Empress Constance, mother of Frederick II., torn, like her, from the convent’s shelter. Beatrice explains to the poet the place of all the saints in the Empyrean--the “heaven of humility where Mary is,” as Dante had sung long before of Beatrice herself in the _Vita Nuova_--and the reason of this temporary apparition in the moon (_Par._ iv.). The other questions solved in this sphere are all connected with Free Will. Rectitude of will is necessary for the gaining of Paradise, and nothing whatever can take away that freedom of the will. “As regards the proper act of the will, no violence can be done to the will”; and, since Piccarda and Constance yielded through fear of greater evil, they fell voluntarily from the state of perfection to which they were called. Freedom of the will is God’s greatest gift to man (_Par._ v. 19-24); hence the sanctity of an accepted vow, wherein this supreme gift is offered to God as victim, although Holy Church has power to commute, save, apparently, in the case of solemn vows of perpetual chastity. It will be observed that this heaven is moved by the Angels, who are severally assigned to individuals as guardians, and who are the bearers of tidings of God’s bounty to men; and, corresponding to this, the questions solved relate to the salvation and guidance of individual souls, and to the great gift of liberty, whereby God’s bounty is specially shown.