For all my friends and colleagues turning 50...

From Four Quartets (Little Gidding)

Let me disclose the gifts reserved for age
To set a crown upon your lifetime's effort.
First, the cold fricton of expiring sense
Without enchantment, offering no promise
But bitter tastelessness of shadow fruit
As body and soul begin to fall asunder.
Second, the conscious impotence of rage
At human folly, and the laceration
Of laughter at what ceases to amuse.
And last, the rending pain of re-enactment
Of all that you have done, and been; the shame
Of things ill done and done to others' harm
Which once you took for exercise of virtue.
Then fools' approval stings, and honour stains.
From wrong to wrong the exasperated spirit
Proceeds, unless restored by that refining fire
Where you must move in measure, like a dancer.