O foolish creatures,
what great ignorance besets you!

[Oh creature sciocche,
quanta ignoranza è quella che v’offende!]

Dante Alighieri (1265-1321) Italian poet

The Divine Comedy [Divina Commedia], Book 1 “Inferno,” Canto 7, l. 70ff (7.70-71) [Virgil] (1309) [tr. Hollander/Hollander (2007)]
    (Source)

Virgil lambasting humanity for not understanding the God-ordained role of Fortune. (Source (Italian)). Alternate translations:

O Mortals without sense,
How great's the Ignorance that you possess!
[tr. Rogers (1782)]

O beings blind! what ignorance
Besets you?
[tr. Cary (1814)]

Ah! sottish creature-tribe!
What scandals doth your ignorance beteem!
[tr. Dayman (1843)]

O foolish creatures, how great is this ignorance that falls upon ye!
[tr. Carlyle (1849)]

Oh! foolish creature! to be blind
What ignorance is that attacks your mind?
[tr. Bannerman (1850)]

Oh, creatures weak and blind,
How ye are hinder'd by your ignorance!
[tr. Johnston (1867)]

O creatures imbecile,
What ignorance is this which doth beset you?
[tr. Longfellow (1867)]

O foolish creatures, how great ignorance is that which makes you trip!
[tr. Butler (1885)]

O creatures dull to see,
What ignorance is this that here offends!
[tr. Minchin (1885)]

O creatures foolish, how great is that ignorance that harms you!
[tr. Norton (1892)]

Besotted race, how deep the ignorance that harasseth you!
[tr. Sullivan (1893)]

O ye insipid creatures.
How great the ignorance which doth oppress
you. [tr. Griffith (1908)]

O foolish creatures, what ignorance is this that besets you!
[tr. Sinclair (1939)]

How heavy the ignorance,
O foolish creatures, that on you is laid.
[tr. Binyon (1943)]

Ah, witless world! Behold the grand
Folly of ignorance!
[tr. Sayers (1949)]

O credulous mankind,
is there one error that has wooed and lost you?
[tr. Ciardi (1954)]

O foolish creatures, how great is the ignorance that besets you!
[tr. Singleton (1970)]

Oh foolish race of man,
how overwhelming is your ignorance!
[tr. Musa (1971)]

O unenlightened creatures,
how deep -- the ignorance that hampers you!
[tr. Mandelbaum (1980)]

How foolish people are!
How great is the ignorance which strikes them down!
[tr. Sisson (1981)]

Foolish creatures,
How great an ignorance plagues you.
[tr. Pinsky (1994), ll. 62-63]

O foolish creatures, how great is the ignorance that injures you!
[tr. Durling (1996)]

O, blind creatures, how great is the ignorance that surrounds you!
[tr. Kline (2002)]

You idiotic creatures,
so greatly hurt by your own ignorance!
[tr. Kirkpatrick (2006)]

O men of foolish minds!
How limited you are, how ignorant!
[tr. Raffel (2010)]

Half-witted mortals, how is it you know
So little even of the ignorance
That starves you?
[tr. James (2013), ll. 66-68]