Making sense of the plot

Sir, – “When we mean to build,/ We first survey the plot, then draw the model;/And when we see the figure of the house,/Then must we rate the cost of the erection;/Which if we find outweighs ability,/What do we then but draw anew the model/ In fewer offices, or at last desist/ To build at all?”

Shakespeare explains how to assess building cost per (iambic) foot (King Henry IV, Part II). – Yours, etc,

GERARD LEE,