at ease vs self-possessed

at ease

prep
  • Allowed to refrain from being in rigid formation. 

  • Free of anxiety; not stressed or tense. 

  • In a relaxed position with the feet apart rather than at attention. 

self-possessed

adj
  • In full control of one's faculties, and having a firm belief in one's abilities; confident, assured and poised. 

How often have the words at ease and self-possessed occurred in a corpus of books? (source: Google Ngram Viewer )