After receiving it, I went online to do some research on the origin of the phrase.

Apparently, the original phrase goes like this –
“I can be a tool of torture or an instrument of inspiration, I can humiliate or humor, hurt or heal.”

And it was by Goethe.

Haim G. Ginott (1922-1973) did used the phrase in his book :
Teacher and child: A book for parents and teachers.

And he still used ‘I’ instead of ‘school’.

However, David Higgins got the credit for changing the word ‘I’ to ‘School’ and this phrase was actually taken from a book on advanced education.

I guess I will make some adjustment to the origin of the quote and will give credit to Goethe as the source of it.

Sharon, thanks for pointing out the problem to me. If not, the quote author will stay in error.