In the words of those who have passed - 2018 edition by Egantx7

Question 14

From a 1968 novel, spoken by the character Master Hand:

You must not change one thing, one pebble, one grain of sand, until you know what good and evil will follow on that act. The world is in balance, in Equilibrium. A wizard's power of Changing and Summoning can shake the balance of the world. It is dangerous, that power. It is most perilous. It must follow knowledge, and serve need. To light a candle is to cast a shadow.

Ursula K. LeGuin