Obreros a no ver dineros a perder—Not to watch your workmen is to lose your money. Sp. Pr.
Obruat illud male partum, male retentum, male gestum imperium—Let that power fall which has been wrongfully acquired, wrongfully retained, and wrongfully administered. Cic.
Obscuris vera involvens—Shrouding, or concealing, truth in obscurity or darkness. Virg.
Obscurity and affectation are the two great faults of style. Macaulay.
Obscurity and Innocence, twin-sisters, escape 30 temptations which would pierce their gossamer armour in contact with the world. Chamfort.
Obscurum per obscurius—Explaining something obscure by what is more obscure.
Obsequium amicos, veritas odium parit—Obsequiousness procures us friends; speaking the truth, enemies. Ter.
Observe this short but certain aphorism, "Forsake all, and thou shalt find all." Thomas à Kempis.
Observe thyself as thy greatest enemy would do; so shalt thou be thy greatest friend. Jeremy Taylor.
Observation is an old man's memory. Swift. 35