over one's head vs recondite

over one's head

adj
  • More complex or confusing than one can understand; beyond one’s comprehension. 

  • Used other than figuratively or idiomatically: see over, head. 

  • More than one can handle; too much (especially in over one's head). 

  • Performing at a level greatly superior to one's usual level of performance. 

  • Directed to someone with authority over the person, so as to avoid requiring the approval of the person himself or herself. 

recondite

adj
  • Difficult to grasp or understand; abstruse, profound. 

  • Little known; esoteric, secret. 

  • Having mastery over one's field, including its esoteric minutiae; learned. 

  • Deliberately employing abstruse or esoteric allusions or references; intentionally obscure. 

noun
  • A recondite (hidden or obscure) person or thing. 

  • A scholar or other person who is recondite, that is, who has mastery over his or her field, including its esoteric minutiae. 

How often have the words over one's head and recondite occurred in a corpus of books? (source: Google Ngram Viewer )