The men who graft the young trees, the little vines, are the cleverest of all, for theirs is a surgeon’s job, as tender and delicate; and these men must have surgeons’ hands and surgeons’ hearts to slit the bark, to place the grafts, to bind the wounds and cover them from the air. These are great men.
– John Steinbeck
The Grapes of Wrath, Chapter 25. Steinbeck uses a medical metaphor to describe the work of those who graft young trees and vines to help produce California’s bumper crop. He likens them to surgeons.