Sign displayed in the Latin classroom at my high school. In the classrooms there, there is a digital clock on the wall in each room with a speaker for the intercom around it as such:
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|           |
|           |
|   -----   |
|  |10:05|  |
|   -----   | 
|           |
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The infamous sign was a piece of oak tag with a part cut out to still reveal the clock. Only it now looked like...
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|   TIME    |
| WILL PASS.|
|   -----   |
|  |10:05|  |
|   -----   | 
| WILL YOU? |
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Presumably, it was there to give pause to students who would endlessly stare at the clock when they should have been paying attention to their Latin, which is notorious for being boring and tedious. As any good Roman would know, time will indeed pass. Whether people who don't pay attention in Latin class will, is up for discussion.