If wisdom was to cease throughout the world, no one would suspect himself of ignorance.
Whoever interrupts the conversation of others to make a display of his fund of knowledge, makes notorious his own stock of ignorance.
However much you are read in theory, if thou hast no practice thou art ignorant
Nothing is so good for an ignorant man as silence; and if he was sensible of this he would not be ignorant.
Whenever you argue with another wiser than yourself in order that others may admire your wisdom, they will discover your ignorance.