Nitere Porro - what does it mean?

Mark Sayer offers us this reflective view on the School motto and his schooldays. 
I am pretty sure that I knocked over a bottle of Nitere Porro in the Chemistry Lab, one lesson. Never mind what year I was in; which decade was it ? Fortunately, someone mopped it up and saved it … and they’re using it again.
In those days, there was no Internet; even the books were in black and white. A dictionary with all the “best” words was something mystical that they kept locked up in things called “libraries”. Only a Highsted student was more difficult to take out. Or given as a school prize (the dictionary). It could be a week or more before an expedition was launched to determine the meaning of a new word. Often, we were too late … and some words had already gone extinct.
These days, we are blessed with online immediate gratification – I mean of the lexicon variety – and eDictionaries abound. We are turning into Alexoids. A “book” is something you do with a delivery slot, and a “page” is something you down. Many words, of course, are foreign – some, even non-Estuarine. And so it was on my journey of enlightenment that I happened upon Google Translate (other brands are available) and the joy of real understanding. If ever you need to know what a foreign term means, just type it in (yes, I’m a little old-fashioned), “page” down to select which language, and discover that they still do a good line in Latin.
Latin is a language
as dead, as dead can be.
It killed the ancient Romans,
but Google translate’s free.
In goes “Nitere Porro” et voila! (or should that be et illic te ?) out comes “lean forward”. Well, I certainly did plenty of that at school and was constantly told to sit up straight. But here comes the best learning: the “swap horizontal” button. Press this, and “lean forward” transforms into “procumbo”. Click again, and “procumbo” becomes “CRASH” (in uppercase, no less). One more click gives “CONLISUS”; the next, “SHOCK”. More clicks deliver successive “SHOCK”s.
So there you have it; a school motto that faithfully enshrines my own school experience:
Lean forwards … CRASH … SHOCK.
Perhaps I should have behaved.