For your amusement, here is another ngram chart, this one for “soul.” Have Plato’s Phaedo and Aristotle’s De Anima made it back onto reading lists? Is the rough coincidence with the decline of feminism and shifting academic fashion in any way meaningful?
The increase in the use of “soul” does not seem to come from soul music:
However, the effect has the same corpus sensitivity noted in my methodological cautions for ngrams. Curiouser and curiouser.