The Manual Oracle and Art of Prudence (El Oráculo Manual y Arte de la Prudencia) from the 17th century resonates strongly in our modern age of information and disinformation where lies have already gone around the world while the truth is still putting on its shoes. Every fool is fully persuaded that he is right, and the more wrong his judgment, the more tenaciously he maintains it. Nothing demands more caution than the truth: it is the lancet of the heart. A single lie destroys an entire reputation for integrity. The deception is considered treason and the deceiver as a traitor, which is worse. However, not all truths can be said: some for our own good, others for the good of others.