Section II
The standing constraint
The hoof, and why the farrier's trade exists.

Every guide in this section
- The standing constraintA domesticated horse on hard ground wears horn faster than it grows, which is the entire reason for shoeing.
- Why the farrier's trade exists at allHot shoeing is metalwork and anatomy at once, and the apprenticeship is long for both reasons.
- The cycle, measured in weeksGrowth rate sets the interval, and the interval sets the yard's calendar.