{Build a tower} (purgon oikodom(8873)ai). A common metaphor,
either a tower in the city wall like that by the Pool of Siloam
( Lu 13:4 ) or a watchtower in a vineyard ( Mt 21:33 ) or a
tower-shaped building for refuge or ornament as here. This
parable of the rash builder has the lesson of counting the cost.
{Sit down} (kathisas). Attitude of deliberation. {First}
(pr(9374)on). First things first. So in verse  31 . {Count}
(ps(8870)hizei). Common verb in late writers, but only here and  Re
13:18  in the N.T. The verb is from ps(8870)hos, a stone, which was
used in voting and so counting. Calculate is from the Latin
_calculus_, a pebble. To vote was to cast a pebble (	ith(886d)i
ps(8870)hon). Luke has Paul using "deposit a pebble" for casting his
vote ( Ac 26:10 ). {The cost} (	(886e) dapan(886e)). Old and common
word, but here only in the N.T. from dapt(935c), to tear, consume,
devour. Expense is something which eats up one's resources.
{Whether he hath wherewith to complete it} (ei echei eis
apartismon). If he has anything for completion of it.
Apartismon is a rare and late word (in the papyri and only here
in the N.T.). It is from apartiz(935c), to finish off (ap- and
artiz(935c) like our articulate), to make even or square. Cf.
ex(8872)tismenos in  2Ti 3:17 .