What is in a school's motto?

Recently, I had occasion to discuss school motto with my son. He is an 8th grader, and it was difficult to find a motto for his school. After I discussed with him what a motto is and so on, I decided to publish this small note on the mottos of the schools that I went to (in reverse chronological order):

1. University of Southern California: Palmam qui meruit ferat. (Let whoever earns the palm bear it.)
2. Indian Institute of Science, Bangalore, India
3. Bangalore University: ज्ञानं विज्ञान सहितं Jnanam Vignana Sahitam (My interpretation: Knowledge must be accompanied by its rational usage or, equivalently, Knowledge accompanied by rational usage is wisdom, but you can read a scholarly interpretation here).
4. National College: श्रद्दाही परमा गतिःShraddha Hi Parama Gatihi.
   

It seems to me that all institutions ought to have a motto: it makes it easier to channel the human energies of the institutions around the motto.