Education is the most radical thing in the world.
To teach the alphabet is to inaugurate a revolution.
To build a schoolhouse is to construct a fort.
Every library is an arsenal filled with the weapons and ammunition of Progress, and every fact is a monitor with sides of iron and a turret of steel.

Robert Green Ingersoll (1833-1899) American lawyer, freethinker, orator

Lecture (1877-06-23), “The Ghosts,” Carson Theater, Carson City, Nevada
    (Source)

Collected in The Ghosts, and Other Lectures (1878)