near. Up a polished step of white marble (which typifies sincerity), a
dark step of cracked stone (symbol of contrition), and one of red
porphyry (emblem of self-sacrifice), Dante arrives at the angel's feet
and humbly begs him to unbar the door. In reply the angel inscribes
upon the poet's brow, by means of his sword, seven _P's_, to represent
the seven deadly sins (in Italian _peccata_), of which mortals must be
purged ere they can enter Paradise.

After bidding Dante have these signs properly effaced, the angel draws
from beneath his ash-hued mantle the golden key of authority and the
silver key of discernment, stating that when St. Peter entrusted them
to his keeping he bade him err "rather in opening than in keeping
fast." Then, the gate open, the angel bids them enter, adding the
solemn warning "he forth again departs who looks behind."

_Canto X._ Mindful of this caution, Dante does not turn, although the
gates close with a clash behind him, but follows his guide along a
steep pathway. It is only after painful exertions they reach the first
terrace of Purgatory, or place where the sin of pride is punished.
They now pass along a white marble cornice,--some eighteen feet
wide,--whose walls are decorated with sculptures which would not have
shamed the best masters of Greek art. Here are represented such
subjects as the Annunciation, David dancing before the Ark, and Trajan
granting the petition of the unfortunate widow. Proceeding along this
path, they soon see a procession of spirits approaching, all bent
almost double beneath huge burdens. As they creep along, one or
another gasps from time to time, "I can endure no more."

_Canto XI._ The oppressed spirits fervently pray for aid and
forgiveness, while continuing their weary tramp around this cornice,