raise the curtain (on something)

1. To begin or commence (something). It's time to raise the curtain on this new project, everyone, so let's not waste any time! After a few delays, the construction crew was finally ready to raise the curtain.

2. To make (something) publicly known; to reveal or disclose the truth (about something). In an attempt to head off a public relations disaster regarding his acceptance of donations, the governor decided to raise the curtain at a press conference.

1. Begin or start, as in It's time to raise the curtain, guys-start shoveling.

2. Make something public, disclose. In this sense, both terms often occur with on, as in We won't know what the new design is until they lift the curtain on it. Both usages, from the mid-1700s, allude to the curtain raised at the beginning of a theatrical performance, revealing the stage.