If the mind is filled with thoughts of Him, if we study the Bible to ascertain more and more clearly what Jesus was, and is, and what He wishes us to be, if we seek to be guided by His will moment by moment, we cannot fail to develop, by His grace, a truly Christ-like spirit.
It is as we continue "beholding as in a glass the glory of the Lord," the glory of His spotless life, and of His complete and absolute surrender to the Father's will, that we are "changed into the same image from glory to glory." Mirrors can only reflect what is before them; in the same way, we can only reflect the likeness of our Master when He is before our minds.