Knowledge has two wings. Conjecture is one wing. Conjecture alone is lacking and cuts short the flight. The one-winged bird continues to struggle, hoping to reach the nest somehow with one wing. And then wisdom shows his shining face. Delivered from conjecture, the bird now spreads both wings (and soars once again).
-Rumi, "The Life and Thought of Rumi"
From "The Bounty of Allah," translated by Aneela Khalid Arshed.