Basil the Great
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.
(in Esai. 2.) Or the tower is a lofty watch-tower fitted for the guardianship of the city and the discovery of the enemy’s approach. In like manner was our understanding given us to preserve the good, to guard against the evil. For the building up whereof the Lord bids us sit down and count our means if we have sufficient to finish.