The end which every man should place before himself is self-mastery and freedom from the world. It is only when he has attained to this goal that he can appear at any moment before God, and will not be surprised by the sudden approach of the day of judgment. Self-mastery is to extend to the inner life of man--Jesus laid great stress upon this--to the words, the thoughts, the heart from which they come forth. Hence the importance of keeping words and thoughts under strict control, of mastering every evil look and every idle word. The feelings of personal honour and vengeance must in like manner be suppressed, for they deprive the soul of its freedom. The disciple is to sit in judgment upon himself, and strive after sincerity and loyal singleness of heart. Nor is he to shrink from any hardship or privation when the need arises. Jesus insists upon the strictest temperance which never rocks itself to sleep in a fancied security; upon watchfulness and prayer, and the constant struggle against temptation. Cut off hand and foot, tear out the eye if they cause thee to offend. It is only by means of this stern self-discipline that it becomes possible for man to be able to appear at any moment before God.
from page 76, The Beginnings of Christianity