O thou son of the Kingdom! All things are beneficial if joined with the love of God; and without His love all things are harmful, and act as a veil between man and the Lord of the Kingdom. When His love is there, every bitterness turneth sweet, and every bounty rendereth a wholesome pleasure. For example, a melody, sweet to the ear, bringeth the very spirit of life to a heart in love with God, yet staineth with lust a soul engrossed in sensual desires. And every branch of learning, conjoined with the love of God, is approved and worthy of praise; but bereft of His love, learning is barren–indeed, it bringeth on madness. Every kind of knowledge, every science, is as a tree: if the fruit of it be the love of God, then is it a blessed tree, but if not, that tree is but dried-up wood, and shall only feed the fire.
Selections from the Writings of Abdu’l-Baha’ #154