“A man looking at a hippopotamus may sometimes be tempted to regard a hippopotamus as an enormous mistake; but he is also bound to confess that a fortunate inferiority prevents him personally from making such mistakes.”

"The Hippopotamus" http://www.cs.rice.edu/~ssiyer/minstrels/poems/848.html

Source: Lamb: The Gospel According to Biff, Christ's Childhood Pal

Variant: Obviously it won't all run smoothly. But it's important to awknowledge that while we may make mistakes, in the long run, we may also learn fromt them.
Source: Lock and Key

Source: Capitalism and Freedom (1962), Ch. 11, Social Welfare Measures, p. 187

Source: A Field Guide to Getting Lost

"The Hippopotamus"
Poems (1920)

Illustrated London News (1924)
Context: The whole modern world has divided itself into Conservatives and Progressives. The business of Progressives is to go on making mistakes. The business of Conservatives is to prevent mistakes from being corrected. Even when the revolutionist might himself repent of his revolution, the traditionalist is already defending it as part of his tradition. Thus we have two great types — the advanced person who rushes us into ruin, and the retrospective person who admires the ruins. He admires them especially by moonlight, not to say moonshine. Each new blunder of the progressive or prig becomes instantly a legend of immemorial antiquity for the snob. This is called the balance, or mutual check, in our Constitution.