On visiting the Moon, Beatrice explains to Dante the reasons for the markings on its surface, describing a simple scientific experiment in optics. She also praises the experimental method in general (Canto II):
"Yet an experiment, were you to try it, could free you from your cavil, and the source of your arts' course springs from experiment."
The waxing and waning of the moon is associated with inconstancy. Consequently, the sphere of the Moon is that of souls who abandoned their vows, and so were deficient in the virtue of fortitude (Canto II). Here Dante and Beatrice meet Piccarda, sister of Dante's friend Forese Donati, who died shortly after being forcibly removed from her convent. They also meet Constance of Sicily, who (Dante believes) was forcibly removed from a convent to marry Henry VI (Canto III). Beatrice discourses on the freedom of the will, the sacredness of vows, and the importance of not collaborating with force (Canto IV):
"for will, if it resists, is never spent, but acts as nature acts when fire ascends, though force a thousand times tries to compel.
So that, when will has yielded much or little, it has abetted force as these souls did: they could have fled back to their holy shelter."
Beatrice explains that a vow is a pact "drawn between a man / and God," in which a person freely offers up his free will as a gift to God. Vows should therefore not be taken lightly, and should be kept once given – unless keeping the vow would be a greater evil, as with Jephthah's and Agamemnon's sacrifice of their daughters (Canto V).
"Yet an experiment, were you to try it,
could free you from your cavil, and the source
of your arts' course springs from experiment."
The waxing and waning of the moon is associated with inconstancy. Consequently, the sphere of the Moon is that of souls who abandoned their vows, and so were deficient in the virtue of fortitude (Canto II). Here Dante and Beatrice meet Piccarda, sister of Dante's friend Forese Donati, who died shortly after being forcibly removed from her convent. They also meet Constance of Sicily, who (Dante believes) was forcibly removed from a convent to marry Henry VI (Canto III). Beatrice discourses on the freedom of the will, the sacredness of vows, and the importance of not collaborating with force (Canto IV):
"for will, if it resists, is never spent,
but acts as nature acts when fire ascends,
though force a thousand times tries to compel.
So that, when will has yielded much or little,
it has abetted force as these souls did:
they could have fled back to their holy shelter."
Beatrice explains that a vow is a pact "drawn between a man / and God," in which a person freely offers up his free will as a gift to God. Vows should therefore not be taken lightly, and should be kept once given – unless keeping the vow would be a greater evil, as with Jephthah's and Agamemnon's sacrifice of their daughters (Canto V).