So, rather than allowing technology to be your master, you become master of it, setting clear boundaries as to where and when you allow it into your life. (entrepreneur.com)
In one word, the moral man can find himself in no situation in life in which he is not master of himself. (religion-online.org)
He can take hold of himself as master of itself — can determine the course of his life, take possession of itself and give of himself. (faith.org.uk)