I found this above the door to Georges Kern's office at SIHH. It really was to carry out the movie-making theme of the booth. But I think it's pretty good:
Even though I studied Latin, I'm not 100% sure of this. If it were "Quid Est Tempus" it would be "What is Time". I guess by putting the "tempus" first, it becomes, loosely, "time is this".