New truths thus are resultants of new experiences and of old truths combined and mutually modifying one another. And since this is the case in the changes of opinion today, there is no reason to assume that it has not been so at all times. It follows that very ancient modes of thought may have survived through all the later changes in men’s opinions. The most primitive ways of thinking may not yet be wholly expunged. Like our five fingers, our ear bones, our rudimentary caudal appendage, or our other “vestigial” peculiarities, they may remain as indelible tokens of events in our race-history.
Pg 74, Pragmatism – William James, ISBN 978-0-7607-4996-8