Schwa surprised me

I am back after a long interlude. In fact, I was extremely busy  studying the phonetics of English language. The most surprising and interesting was the schwa sound in English which does not have a definite origin. The most surprising is the fact that it is the commonest sound in english speech, but does not have definite letter from which it may evolve. It can evolve from any English vowel. I am further busy studying English sound system and also have started writing a book on functional grammar. I hope my readers or blog friends would not mind if I don't turn up frequently. I wish to have your good wishes for my little pursuit. Please pray for me from the core of your heart. This will be a great favour.