The Talmud: Selections, by H. Polano, , at sacred-texts.com
Nothing in the World without its Use.
David, King of Israel, was once lying upon his couch and many thoughts were passing through his mind.
"Of what use in this world is the spider?" thought he; "it but increases the dust and dirt of the world, making places unsightly and causing great annoyance."
Then he thought of an insane man:
"How unfortunate is such a being. I know that all things are ordained by God with reason and purpose, yet
this is beyond my comprehension; why should men be born idiots, or grow insane?"
Then the mosquitoes annoyed him, and the king thought:
"What can the mosquito be good for? why was it created in the world? It but disturbs our comfort, and the world profits not by its existence."
Yet King David lived to discover that these very insects, and the very condition of life, the being of which he deplored, were ordained even to his own benefit.
When he fled from before Saul, David was captured in the land of the Philistines by the brothers of Goliath, who carried him before the king of Gath, and it was only by pretending idiocy that he escaped death, the king deeming it impossible that such a man could be the kingly David; as it is written, "And he disguised his reason before their eyes, and played the madman in their hands, and scribbled on the doors of the gate, and let his spittle run down upon his beard" (Sam. 12-16).
Upon another occasion David hid himself in the cave of Adullam, and after he had entered the cave it chanced that a spicier spun a web over the opening thereto. His pursuers passed that way, but thinking that no one could have entered the cave protected by the spider's web without destroying it, they continued on their way.
The mosquito also was of service to David when he entered the camp of Saul to secure the latter's weapon. While stooping near Abner, the sleeping man moved and placed his leg upon David's body. If he moved, he would awake Abner and meet with death, if he remained in that position morning would dawn and bring him death; he knew not what to do, when a mosquito alighted upon Abner's leg; he moved it quickly, and David escaped.
Therefore sang David:
"All my bones shall say, O Lord, who is like unto Thee."