The civilest way of describing an ignoramus

From the author’s footnote to Anecdotes – Juvenal in v.1 of Thomas de Quincey’s Posthumous Works:

The passion which made Juvenal a poet.‘ The scholar needs no explanation; but the reader whose scholarship is yet amongst his futurities (which I conceive to be the civilest way of describing an ignoramus) must understand that Juvenal, the Roman satirist, who was in fact a predestined poet in virtue of his ebullient heart, that boiled over once or twice a day in anger that could not be expressed upon witnessing the enormities of domestic life in Rome, was willing to forego all pretensions to natural power and inspiration for the sake of obtaining such influence as would enable him to reprove Roman vices with effect.

The robb’d that smiles steals something from the thief

Some polonian platitudes from Othello (1.3), as the Duke soothes Brabantio over Desdemona’s elopement:

DUKE OF VENICE
Let me speak like yourself, and lay a sentence,
Which, as a grise or step, may help these lovers
Into your favour.
When remedies are past, the griefs are ended
By seeing the worst, which late on hopes depended.
To mourn a mischief that is past and gone
Is the next way to draw new mischief on.
What cannot be preserved when fortune takes
Patience her injury a mockery makes.
The robb’d that smiles steals something from the thief;
He robs himself that spends a bootless grief.

I want to connect the bolded line with Juvenal 10.22 (cantabit vacuus coram latrone viator – ‘the empty-handed traveler will sing in the robber’s face’) but it feels too weak a link.

At least Brabantio gets his own back in his reply:

BRABANTIO
So let the Turk of Cyprus us beguile;
We lose it not, so long as we can smile.
He bears the sentence well that nothing bears
But the free comfort which from thence he hears,
But he bears both the sentence and the sorrow
That, to pay grief, must of poor patience borrow.
These sentences, to sugar, or to gall,
Being strong on both sides, are equivocal:
But words are words; I never yet did hear
That the bruised heart was pierced through the ear.
I humbly beseech you, proceed to the affairs of state.