Theophylact of Ohrid
Catena Aurea · Lukasevangelium 14
For which of you, intending to build a tower, sitteth not down first, and counteth the cost, whether he have sufficient to finish it? Lest haply, after he hath laid the foundation, and is not able to finish it, all that behold it begin to mock him, Saying, This man began to build, and was not able to finish. Or what king, going to make war against another king, sitteth not down first, and consulteth whether he be able with ten thousand to meet him that cometh against him with twenty thousand? Or else, while the other is yet a great way off, he sendeth an ambassage, and desireth conditions of peace. So likewise, whosoever he be of you that for-saketh not all that he hath, he cannot be my disciple.
For we ought not to lay a foundation, i. e. begin to follow Christ, and not bring the work to an end, as those of whom St. John writes, That many of his disciples went backward. (John 6:66.) Or by the foundation understand the word of teaching, as for instance concerning abstinence. There is need therefore of the above-mentioned foundation, that the building up of our works be established, a tower of strength from the face of the enemy. (Ps. 61:3.) Otherwise, man is laughed at by those who see him, men as well as devils.