Perga 6

     I saw that gentle band silently next
Look up, as if in expectation held,
Pale and in lowly guise; and from on high
I saw forth issuing descend beneath
Two angels with two flame-illumin'd swords,
Broken and mutilated at their points.
Green as the tender leaves but newly born,
Their vesture was, the which by wings as green
Beaten, they drew behind them, fann'd in air.
A little over us one took his stand,
The other lighted on the' Opposing hill,
So that the troop were in the midst contain'd.
     Well I descried the whiteness on their heads;
But in their visages the dazzled eye
Was lost, as faculty that by too much
Is overpower'd.  "From Mary's bosom both
Are come," exclaim'd Sordello, "as a guard
Over the vale, ganst him, who hither tends,
The serpent."  Whence, not knowing by which path
He came, I turn'd me round, and closely press'd,
All frozen, to my leader's trusted side.
     Sordello paus'd not: "To the valley now
(For it is time) let us descend; and hold
Converse with those great shadows: haply much
Their sight may please ye."  Only three steps down
Methinks I measur'd, ere I was beneath
Nino, thou courteous judge! what joy I felt,
When I perceiv'd thou wert not with the bad!
     No salutation kind on either part
Was left unsaid.  He then inquir'd: "How long
Since thou arrived'st at the mountain's foot,
Over the distant waves?"—"O!" answer'd I,
"Through the sad seats of woe this morn I came,
And still in my first life, thus journeying on,
The other strive to gain."  Soon as they heard
My words, he and Sordello backward drew,
As suddenly amaz'd.  To Virgil one,
The other to a spirit turn'd, who near
Was seated, crying: "Conrad! up with speed:
Come, see what of his grace high God hath will'd."
Then turning round to me: "By that rare mark
Of honour which thou ow'st to him, who hides
So deeply his first cause, it hath no ford,
When thou shalt be beyond the vast of waves.
Tell my Giovanna, that for me she call
There, where reply to innocence is made.

     The Spirit (who to Nino, when he call'd,

Had come), from viewing me with fixed ken,
Through all that conflict, loosen'd not his sight.
       The love
I bore my people is now here refin'd."
     "In your dominions," I answer'd, "ne'er was I.
But through all Europe where do those men dwell,
To whom their glory is not manifest?
The fame, that honours your illustrious house,
Proclaims the nobles and proclaims the land;
So that he knows it who was never there.

The Lawn with the Kings and Angel
William Blake's Illustrations of Dante
Purgatorio VIII

In a small , usually wooded valley or vale. we might see
Dante and his mentor, with another figure, perhaps a king;
they are standing in front of a multitude or audience.

The 'lawn' is a leafy place


From UTex:
Like Virgil, Sordello is a poet from Mantua (a city in northern Italy) but he is from the Middle Ages (13th century, a generation or two before Dante) not the period of the Roman empire. Following a series of scandals (e.g., the alleged abduction of a nobleman's wife), Sordello left Italy and passed through various courts in Spain, France, and Provence. In 1241 he found stable residence at the court of Raymond Berenger, Count of Provence. Here Sordello worked in various administrative capacities until, having attained knighthood, he returned to Italy, where he died sometime around 1269. Sordello wrote poems in Provençal, including one on courtly virtue and another contrasting the good qualities of a dead nobleman with the deficiencies of contemporary European rulers. 
 
Virgil and Dante see Sordello seated off by himself, like a lion at rest attentively eyeing the travelers as they approach. He is proud and dignified but very affectionate with Virgil when he learns they are from the same city. The love shown between Sordello and Virgil because of their common homeland triggers a long authorial diatribe against the violence, corruption, and lack of effective leadership up and down the Italian peninsular in Dante's time (6.76-151). Sordello accompanies Dante and Virgil to the Valley of Rulers in the Ante-Purgatory.