I didn’t say anything about mastering all areas, I suggested a measure of competence. In an emergency. A psychiatrist better know how to set a broken bone or deliver a baby even if it’s not her area of expertise.
You know, a bit more happiness is available to people who dont try to take every word literally and pounce on a generalization.
Yes,my use of "mastering" was unwise."A clear familiarity" might have been a better way to put it.