They didn't understand what they were doing. I'm afraid that will be on the tombstone of the human race. I hope it's not. We might get lucky.

They lost their humanity, in our eyes, because of a certain willed ignorance on their part.

The lot of critics is to be remembered by what they failed to understand.

The next generation is going to have terrible handwriting.

Those who do not know their history, his thought careened, are doomed to keep stepping in it. Alas, so were those who did, it seemed.

A pity she did not understand them!

Here, I thought, I had found the human race in its final stages of decadence—perverse, insouciant, without ambition. And I could not blame them. After all, they had no future.

Those who don't know history are doomed to repeat it.

Science explained people, but could not understand them.

In the course of a long experience of the human race, I have learned that you can never make them understand anything, unless you rub it in.

The human race, whose intelligence dates back only a single tick of the astronomical clock, could hardly hope to understand so soon what it all means.

They tried to be too clever — -and that was their undoing.

Never blame the man: his hard-pressed
Ancestors formed him: the other anthropoid apes were safe
In the great southern rain-forest and hardly changed
In a million years: but the race of man was made
By shock and agony…
… a wound was made in the brain
When life became too hard, and has never healed.
It is there that they learned trembling religion and blood-
sacrifice,
It is there that they learned to butcher beasts and to slaughter
men,
And hate the world.

The end of the human race will be that it will eventually die of civilization.