啓 - disclose, open, say

enlightenment; illumination

(divine) revelation

Dear (so and so); Dear Sir; Dear Madam; To Whom It May Concern

enlightenment; development; edification; public awareness; illumination; education; inspiration

Dear Sir or Madam, in reply to your letter ...

Dear Sir or Madam

dispensing with the preliminaries ...

postscript; P.S.; PS

Keigaku (publisher)

"awakening of insects" solar term (approx. March 6, the day on which hibernating insects are said to come out of the ground)

this will just be a short note; I'm writing to tell you

to enlighten; to edify