Caesar was referring to gaming dice when he said "The die is cast". He meant that he was taking a bold chance by crossing the Rubicon River with his army, indicating that he intended to overthrow the emperor. He was also indicating that he was making an irrevocable decision. When I was about ten years old, I was familiar with various forging processes & thought the phrase referred to a forging die, not realizing that metallurgy was not that advanced at the time of Julius Caesar. It is amusing that the meaning of both interpretations is quite similar. Caesar was stating that he was making an irrevocable decision. When a forging die is finally cast, there is no way to change the shape of the objects to be forged. All that is missing is the chance taking implied by the dice metaphor. I did not learn of my mistake until I was an adult. When I mentioned my erroneous interpretation to a girl friend, she laughed because she had a similar misunderstanding of the Caesar phrase. "Cast" is also an archaic term for dying material. My friend had a grandmother who used the phrase "The dye is cast." The grandmother once explained to my friend that once the dye is cast, you can never recover the original color of the material. You can only cast a color darker than the current color. Once again, an interpretation which indicates an irrevocable decision.