The young Ensign approached the crusty old Chief and asked
him about the origin of the commissioned office insignias.

"Well, Ensign, it's history and tradition. First, we give
you a gold bar representing that you're valuable BUT
malleable. The silver bar of a Lieutenant Junior Grade
represents value, but less malleable. When you make
Lieutenant, you're twice as valuable so we give you two
silver bars. As a Captain, you soar over military masses,
hence the eagle. As an Admiral, you're obviously a star.
That answer your question?"

"Yeah, but what about Commanders and Lieutenant Commanders?"

"Now that goes waaaaaay back in history. Back to the
Garden of Eden even. You see, we've always covered our
pricks with leaves . . . "