Proportion is that agreeable harmony between the several parts of a building, which is the result of a just and regular agreement of them with each other; the height to the width, this to the length, and each of these to the whole.

Economy consists in a due and proper application of the means afforded according to the ability of the employer and the situation chosen; care being taken that the expenditure is prudently conducted.

Consistency is found in that work whose whole and detail are suitable to the occasion. It arises from circumstance, custom, and nature.

Vitruvius Quotes