If Allah had wanted to create Adam from a light whose glare would have dazzled the eyes, whose handsomeness would have amazed the wits and whose smell would have caught the breath, He could have done so; and if He had done so, they would have bowed to him in humility and the trial of the angels through him would have become easier. But Allah, the Glorified, tries His creatures, by means of those things whose real nature they do not know, in order to distinguish (good and bad) for them through the trial, and to remove vanity from them and keep them aloof from pride and self-admiration. (Imam Ali (AS) sermon #191)
