Not sure how things compare to today’s culture but I ask my father “a Master Plumber” how many generations it took to train him and who trained him.
His answer was that he learned his trade in six years and no one trained him. Observation and curiosity lead him to techniques that were successful.
The human mind can create almost anything and sometimes (seeming) out of thin air. Never underestimate the ability of man-kind.
© Charles N. Pope, US Library of Congress. All rights reserved.