Under sackcloth there is something else. 25 Sp. and Port. Pr.
Under the sky is no uglier spectacle than two men with clenched teeth and hell-fire eyes hacking one another's flesh, converting precious living bodies and priceless living souls into nameless masses of putrescence, useful only for turnip-manure. Carlyle.
Under the weight of his knowledge, a man cannot move so lightly as in the days of his simplicity. Ruskin.
Under white ashes there often lurk glowing embers. Dan. Pr.
Underground / Precedency's a jest; vassal and lord, / Grossly familiar, side by side consume. Blair.
Underneath this stone doth lie / As much 30 beauty as could die; / Which in life did harbour give / To more virtue than doth live. Jonson, on Elizabeth, Countess of Rutland.
Understanding is a wellspring of life unto him that hath it. Bible.
Understanding is the most important matter in everything. Hans Andersen.
Understanding is the wages of a lively faith, and faith is the reward of a humble ignorance. Quarles.
Undertake no more than you can perform. Pr.