Until now, he.d always thought he could turn back.
I can't turn back time, but I can do something about the future.
He takes no heed of his rider, pays no attention whether he be on his back or not, walks straight on when once set agoing, merely because he is too stupid to turn aside, and then should some tempting thorn or green branch allure him out of the path, continues to walk on in the new direction simply because he is too dull to turn back into the right road.
His armies crossed the plains beyond the Caspian, penetrated the wild mountain passes northwest of India, and did not turn back until they had entered on the Indo-Gangetic plain.
We must now turn back to a most difficult subject - the growth of the Liturgy.