All the sites I found list it as anonymous. It was used by Senator Warner in a speech, but I doubt he composed the saying:
Simply put, to teach is to touch a life forever.
How true that is. I venture to say that every one of us can remember at least one teacher and the special influence he or she had on our lives.
~ U.S. Senator, John W. Warner
Quote from A Gentle Madness
(Bibliophiles, Bibliomanes, and the Eternal Passion for Books)
by Nicholas Basbanes
"The North Carolina author Reynolds Price was doodling on a paper placemat in a Harvard Square cafe one morning in 1992 when he told me about the copy of "Paradise Lost" he had bought for himself five years earlier after surviving extensive treatment for spinal cancer.
Price says that he had always been a book collector and that he teaches a
course on John Milton at Duke University, but stressed that the thin volume means considerably more to him than love of the great poet's work:
"Milton was in his early forties and I was in my early fifties when we both underwent a physically devastating illness, and in both our lives the experience led to some kind of mysterious renewal of good work,"
He explained. "Milton wrote his best books after he lost his sight. I have written eleven volumes since I had cancer, and it represents some of the best work I have ever done. My copy of "Paradise Lost" once belonged to Deborah Milton Clarke, the daughter who took Milton's dictation after he went blind. For me, it was like the apostolic succession.
I was touching the hand that touched the hand that touched the Hand."