The way of the Lord must be prepared within the heart; for great and spacious is the heart of man, as if it were a whole world. But see its greatness, not in bodily quantity, but in the power of the mind which enables it to encompass so great a knowledge of the truth. Prepare, therefore, in your hearts the way of the Lord, by a worthy manner of life. Keep straight the path of your life, so that the words of the Lord may enter in without hindrance.

Origen, Homilies on Luke 21.5.7, quoted in Thomas C. Oden & Christopher A. Hall (ed), Mark, Ancient Christian Commentary on Scripture(Intervarsity Press, 2005) 2.