King David once questioned the purpose of three seemingly useless or harmful creatures: the gnat, the spider, and the fool. "Why did God create these things?" he asked. "The gnat bites and accomplishes nothing. The spider spins a web that serves no purpose. And the fool — what possible function does a fool serve in the world?"
God answered David not with words but with experience. The Midrash (Midrash Psalms 57, Targum Psalms) records three incidents in which each of these "useless" creatures saved David's life.
First, the spider. When David was fleeing from King Saul and hid in a cave, a spider spun a web across the cave's entrance. Saul's soldiers saw the unbroken web and assumed no one could have entered recently. They moved on. The spider's "useless" web saved the future king of Israel.
Second, the gnat. When David infiltrated Saul's camp and stood over the sleeping king, he could have killed him. But a gnat bit Saul's general Abner, causing him to roll over in his sleep and trap David's escape route. The disturbance awakened the camp and forced David to flee — preventing him from committing an act of regicide that would have stained his hands forever.
Third, the fool. When David was captured by the Philistine king Achish of Gath, he pretended to be insane — drooling, scrawling on the gates, behaving like a madman. Achish released him, saying: "Do I lack madmen that you bring this fellow to rave in my presence?" (1 Samuel 21:15). David's impersonation of a fool saved his life.
From that day forward, David never questioned the purpose of any creature. God creates nothing without reason.