The application of architecture, engineering, math combined with the art of work working. Wood is a renewable resource that must be harvested in a manner that will ensure the stable supply for at least seven generations.
Carpentry is a skill that our civilization is built on and in our "modern" times is often under-appreciated. Luckily there are lots of folks that practice this as hobbyists and professionals, and who are generally willing to teach and pass on their skills.