Why were Eli Whitneys interchangeable parts such an amazing idea for its time?

Interchangeable parts, popularized in America when Eli Whitney used them to assemble muskets in the first years of the 19th century, allowed relatively unskilled workers to produce large numbers of weapons quickly and at lower cost, and made repair and replacement of parts infinitely easier.

Explanation: :)

c (: when ulrich considers throwing georg the flask

the eye wink at the hand; yet let that be / which the eye fears, when it is done, to see.