If—

If— is a poem by Rudyard Kipling, written in 1895 and first published in Rewards and Fairies (1910). It is reproduced here in full; the work is in the public domain.

If you can keep your head when all about you
    Are losing theirs and blaming it on you,
If you can trust yourself when all men doubt you,
    But make allowance for their doubting too;
If you can wait and not be tired by waiting,
    Or being lied about, don't deal in lies,
Or being hated, don't give way to hating,
    And yet don't look too good, nor talk too wise:

If you can dream—and not make dreams your master;
    If you can think—and not make thoughts your aim;
If you can meet with Triumph and Disaster
    And treat those two impostors just the same;
If you can bear to hear the truth you've spoken
    Twisted by knaves to make a trap for fools,
Or watch the things you gave your life to, broken,
    And stoop and build 'em up with worn-out tools:

If you can make one heap of all your winnings
    And risk it on one turn of pitch-and-toss,
And lose, and start again at your beginnings
    And never breathe a word about your loss;
If you can force your heart and nerve and sinew
    To serve your turn long after they are gone,
And so hold on when there is nothing in you
    Except the Will which says to them: 'Hold on!'

If you can talk with crowds and keep your virtue,
    Or walk with Kings—nor lose the common touch,
If neither foes nor loving friends can hurt you,
    If all men count with you, but none too much;
If you can fill the unforgiving minute
    With sixty seconds' worth of distance run,
Yours is the Earth and everything that's in it,
    And—which is more—you'll be a Man, my son!

The whole poem is one sentence. Thirty lines of conditionals stack up before the main clause finally lands in the last two (Yours is the Earth and everything that's in it), which means the payoff only exists if the conditions hold. The grammar is the argument.

Kipling wrote it as advice to his son John, and the virtues it lists are almost all negative ones: don't deal in lies, don't give way to hating, don't look too good, don't talk too wise. It is less a description of what to achieve than of what to withstand.

The line most often quoted on its own (treat those two impostors just the same) is also the one most often mistaken for indifference. Kipling calls Triumph and Disaster impostors, not illusions. Both arrive claiming to be verdicts on you. Neither one is.